GET WIDGETS: 2010

Wednesday, July 7, 2010

PHP - Printing a random file from a folder

This is one of the easiest ways to ad management out there. It selects a random file from the directory you chose and displays them randomly.
This code is useful if you have ad codes in different files and want to randomly rotate them.

$rmdlist='';

//$rmd_folder is the variable that choses the directory that the files will be in. Mine is images/rmd-img/

// Make sure you DO NOT forget about the "/" at the end or this will not work.

$rmd_folder = "images/rmd-img/";

mt_srand((double)microtime()*1000);

//use the directory class

$imgs = dir($rmd_folder);

//reads all the files from the directory you chose and ads them to a list.

while ($file = $imgs->read()) {

if (eregi("gif", $file) || eregi("jpg", $file) || eregi("png", $file))

$rmdlist .= "$file ";

} closedir($imgs->handle);

//now, put all the images into a array

$rmdlist = explode(" ", $rmdlist);

$no = sizeof($rmdlist)-2;

//now, generate a randon number from 0 - the number of images in the directory you chose.

$random = mt_rand(0, $no);

$image = $rmdlist[$random];

//display's the image.

echo '';

Show headline ticker in your blog

Display a cool headlines ticker in your blogs and change the way it looks!

With our "Headlines widget" you can put a customized latest posts ticker directly into your blogs unlike a normal code copy and past process.

Like our earlier headlines scroller widget, we developed a clean interface to take the full advantage of this cool feature:

MySql Tutorial 6 - Using mysql in Batch Mode

In the previous sections, you used mysqlinteractively to enter queries and view the results. You can also run mysql in batch mode. To do this, put the commands you want to run in a file, then tell mysql to read its input from the file:

shell> mysql < batch-file

If you are running mysql under Windows and have some special characters in the file that cause problems, you can do this:

C:\> mysql -e "source batch-file"

If you need to specify connection parameters on the command line, the command might look like this:

shell> mysql -h host -u user -p < batch-file

Enter password: ********

When you use mysql this way, you are creating a script file, then executing the script.

If you want the script to continue even if some of the statements in it produce errors, you should use the --force command-line option.

Why use a script? Here are a few reasons:

If you run a query repeatedly (say, every day or every week), making it a script allows you to avoid retyping it each time you execute it.

You can generate new queries from existing ones that are similar by copying and editing script files.

Batch mode can also be useful while you're developing a query, particularly for multiple-line commands or multiple-statement sequences of commands. If you make a mistake, you don't have to retype everything. Just edit your script to correct the error, then tell mysql to execute it again.

If you have a query that produces a lot of output, you can run the output through a pager rather than watching it scroll off the top of your screen:
```
shell> mysql < batch-file | more
```

You can catch the output in a file for further processing:
```
shell> mysql < batch-file > mysql.out
```

You can distribute your script to other people so that they can also run the commands.

Some situations do not allow for interactive use, for example, when you run a query from a cron job. In this case, you must use batch mode.

The default output format is different (more concise) when you run mysql in batch mode than when you use it interactively. For example, the output of SELECT DISTINCT species FROM pet looks like this when
mysql is run interactively:

+---------+
| species |
+---------+
| bird    |
| cat     |
| dog     |
| hamster |
| snake   |
+---------+

In batch mode, the output looks like this instead:

species
bird
cat
dog
hamster
snake

If you want to get the interactive output format in batch mode, use mysql -t. To echo to the output the commands that are executed, use mysql -vvv.

You can also use scripts from the mysql prompt by using the source command or
\. command:

mysql> source filename;

mysql> \. filename

MySql Tutorial 5 - Getting Information About Databases and Tables

What if you forget the name of a database or table, or what the
structure of a given table is (for example, what its columns are
called)? MySQL addresses this problem through several statements
that provide information about the databases and tables it
supports.

You have previously seen SHOW DATABASES, which
lists the databases managed by the server. To find out which
database is currently selected, use the
DATABASE() function:

mysql> SELECT DATABASE();
+------------+
| DATABASE() |
+------------+
| menagerie  |
+------------+

If you have not yet selected any database, the result is
NULL.

To find out what tables the default database contains (for
example, when you are not sure about the name of a table), use
this command:

mysql> SHOW TABLES;

+---------------------+
| Tables_in_menagerie |
+---------------------+
| event               |
| pet                 |
+---------------------+

The name of the column in the output produced by this statement is
always
Tables_in_db_name,
where db_name is the name of the
database. See Section 12.5.4.25, “SHOW TABLES Syntax”, for more information.

If you want to find out about the structure of a table, the
DESCRIBE command is useful; it displays
information about each of a table's columns:

mysql> DESCRIBE pet;
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| name    | varchar(20) | YES  |     | NULL    |       |
| owner   | varchar(20) | YES  |     | NULL    |       |
| species | varchar(20) | YES  |     | NULL    |       |
| sex     | char(1)     | YES  |     | NULL    |       |
| birth   | date        | YES  |     | NULL    |       |
| death   | date        | YES  |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+

Field indicates the column name,
Type is the data type for the column,
NULL indicates whether the column can contain
NULL values, Key indicates
whether the column is indexed, and Default

specifies the column's default value. Extra
displays special information about columns; for example, if a
column was created with the AUTO_INCREMENT
option, this is shown here.

MySql Tutorial 4 - Retrieving Information from a Table

Just a database system would be useless without some way to write data to the database files, a database would be similarly useless if there were no way to extract the stored data. Amongst the available SQL statements, one of the most frequently used is the SELECT statement. The purpose of the SELECT statement is to retrieve data from a database table based on specified criteria. In this chapter we will cover the use of the SELECT statement in detail.

1. Retrieving a Single Column

2. Using SELECT to Retrieve Mutiple Columns

3. Restricting Number of Results

4. Eliminating Duplicate Values from Results

5. Summary

Retrieving a Single Column

The most basic of SELECT statements simply retrieves a single column of all the rows of a table. The following SQL statements select a database named extract all the product_description column entries in the product table:

USE MySampleDB;
SELECT product_description FROM product;

Once executed, this command will display a list of every product description contained in the product table:

+-------------------+
| prod_desc |
+-------------------+
| CD Writer |
| Cordless Mouse |
| SATA Disk Drive |
| Ergonomic Keyboard|
+-------------------+
4 rows in set (0.00 sec)

Using SELECT to Retrieve Mutiple Columns

So far we have seen how easy it is to extract a single column from each row of a table. In the real world, it is more likely that information from more than one column will need to be retrieved. Fortunately the SELECT statement makes this task easy too. In fact, all that needs to be done is to specify the columns names after the SELECT statement, each separated by a comma. For example, to retrieve data from three columns in our database table:

SELECT prod_code, prod_name, prod_desc FROM product;

The above command will generate the following output if executed from within the mysql tool:

+-----------+--------------------------+-------------------+
| prod_code | prod_name | prod_desc |
+-----------+--------------------------+-------------------+
| 1 | CD-RW Model 4543 | CD Writer |
| 2 | EasyTech Mouse 7632 | Cordless Mouse |
| 3 | WildTech 250Gb 1700 | SATA Disk Drive |
| 4 | Microsoft 10-20 Keyboard | Ergonomic Keyboard|
+-----------+--------------------------+-------------------+
4 rows in set (0.01 sec)

Whilst this approach works fine if you do not want to display all columns in a table, it can become cumbersome in situations where a table contains many columns and you want to list all columns. An easier way to achieve this than specifying every column is to use the wildcard symbol (*) in place of the column names. For example:

SELECT * FROM product;

Restricting Number of Results

When retrieving data from a table it is possible to limnit the number of results that are returned by the SELECT statement using the LIMIT keyword. This keyword is followed by a number indicating how may rows are to be retrieved:

SELECT * FROM product LIMIT 10;

The above command will retrieve only 10 rows from the database table. Both the start and end rows can be specified for reading further into a table. The following example, therefore, extracts rows 10 through 15 of the table:

SELECT * FROM product LIMIT 10, 15;

Eliminating Duplicate Values from Results

It is not unusual for a column value combination to be duplicated throughout multiple rows. This means that when retrieving data, and particularly when retrieving data for a single column in a table, that duplicated values may appear in the results. For example:

SELECT prod_desc FROM product;
+-------------------+
| prod_desc |
+-------------------+
| CD Writer |
| SATA Disk Drive |
| Cordless Mouse |
| SATA Disk Drive |
| Ergonmoc Keyboard |
| CD Writer |
+-------------------+

As we can see from in the above output, our fictitious on-line store sells more than one type of disk drive and CD writer. Whilst the product codes and names are likely to be unique, the descriptions have duplications. If we wanted to get a list of product descriptions devoid of duplications we would use the DISTINCT keyword:

SELECT DISTINCT prod_desc FROM product;

This would result in the following output:

+-------------------+
| prod_desc |
+-------------------+
| CD Writer |
| SATA Disk Drive |
| Cordless Mouse |
| Ergonmoc Keyboard |
+-------------------+

Summary

In the chapter we have looked at the ease with which data can be retrieved from a database using the SELECT statement. With the basics covered, it is time to move on to more advance data retrieval topics.

MySql Tutorial 3 – Creating and Using a Database

Contents
1. Creating and Selecting a Database
2. Creating a Table
3. Loading Data into a Table

Once you know how to enter commands, you are ready to access a database.

Suppose that you have several pets in your home (your menagerie) and you would like to keep track of various types of information about them. You can do so by creating tables to hold your data and loading them with the desired information. Then you can answer different sorts of questions about your animals by retrieving data from the tables. This section shows you how to:

Create a database

Create a table

Load data into the table

The menagerie database is simple (deliberately), but it is not difficult to think of real-world situations in which a similar type of database might be used. For example, a database like this could be used by a farmer to keep track of livestock, or by a veterinarian to keep track of patient records. A menagerie distribution containing some of the queries and sample data used in the following sections can be obtained from the MySQL Web site. It is available in both compressed tar file and Zip formats at http://dev.mysql.com/doc/.

Use the SHOW statement to find out what databases currently exist on the server:

mysql> SHOW DATABASES;
+----------+
| Database |
+----------+
| mysql    |
| test     |
| tmp      |
+----------+

The mysql database describes user access privileges. The test database often is available as a workspace for users to try things out.

The list of databases displayed by the statement may be different on your machine; SHOW DATABASES does not show databases that you have no privileges for if you do not have the SHOW DATABASES privilege. See Section 12.5.4.8, “SHOW DATABASES Syntax”.

If the test database exists, try to access it:

mysql> USE test
Database changed

Note that USE, like QUIT, does not require a semicolon. (You can terminate such statements with a semicolon if you like; it does no harm.) The USE statement is special in another way, too: it must be given on a single line.

You can use the test database (if you have access to it) for the examples that follow, but anything you create in that database can be removed by anyone else with access to it. For this reason, you should probably ask your MySQL administrator for permission to use a database of your own. Suppose that you want to call yours menagerie. The administrator needs to execute a command like this:

mysql> GRANT ALL ON menagerie.* TO 'your_mysql_name'@'your_client_host';

where your_mysql_name is the MySQL user name assigned to you and your_client_host is the host from which you connect to the server.

Top

1. Creating and Selecting a Database

If the administrator creates your database for you when setting
up your permissions, you can begin using it. Otherwise, you need
to create it yourself:

mysql> CREATE DATABASE menagerie;

Under Unix, database names are case sensitive (unlike SQL
keywords), so you must always refer to your database as
menagerie, not as
Menagerie, MENAGERIE, or
some other variant. This is also true for table names. (Under
Windows, this restriction does not apply, although you must
refer to databases and tables using the same lettercase
throughout a given query. However, for a variety of reasons, our
recommended best practice is always to use the same lettercase
that was used when the database was created.)

Note

If you get an error such as ERROR 1044 (42000):
Access denied for user 'monty'@'localhost' to database
'menagerie' when attempting to create a database,
this means that your user account does not have the necessary
privileges to do so. Discuss this with the administrator or
see Section 5.4, “The MySQL Access Privilege System”.

Creating a database does not select it for use; you must do that
explicitly. To make menagerie the current
database, use this command:

mysql> USE menagerie;
Database changed

Your database needs to be created only once, but you must select
it for use each time you begin a mysql
session. You can do this by issuing a USE
statement as shown in the example. Alternatively, you can select
the database on the command line when you invoke
mysql. Just specify its name after any
connection parameters that you might need to provide. For
example:

shell> mysql -h host -u user -p menagerie
Enter password: ********

Note that menagerie in the command just shown
is not your password. If you
want to supply your password on the command line after the
-p option, you must do so with no intervening
space (for example, as -pmypassword,
not as -p mypassword).
However, putting your password on the command line is not
recommended, because doing so exposes it to snooping by other
users logged in on your machine.
Top

2. Creating a Table

Creating the database is the easy part, but at this point it's
empty, as SHOW TABLES tells you:

mysql> SHOW TABLES;
Empty set (0.00 sec)

The harder part is deciding what the structure of your database
should be: what tables you need and what columns should be in
each of them.

You want a table that contains a record for each of your pets.
This can be called the pet table, and it
should contain, as a bare minimum, each animal's name. Because
the name by itself is not very interesting, the table should
contain other information. For example, if more than one person
in your family keeps pets, you might want to list each animal's
owner. You might also want to record some basic descriptive
information such as species and sex.

How about age? That might be of interest, but it's not a good
thing to store in a database. Age changes as time passes, which
means you'd have to update your records often. Instead, it's
better to store a fixed value such as date of birth. Then,
whenever you need age, you can calculate it as the difference
between the current date and the birth date. MySQL provides
functions for doing date arithmetic, so this is not difficult.
Storing birth date rather than age has other advantages, too:

You can use the database for tasks such as generating
reminders for upcoming pet birthdays. (If you think this
type of query is somewhat silly, note that it is the same
question you might ask in the context of a business database
to identify clients to whom you need to send out birthday
greetings in the current week or month, for that
computer-assisted personal touch.)

You can calculate age in relation to dates other than the
current date. For example, if you store death date in the
database, you can easily calculate how old a pet was when it
died.

You can probably think of other types of information that would
be useful in the pet table, but the ones
identified so far are sufficient: name, owner, species, sex,
birth, and death.

Use a CREATE TABLE statement to specify the
layout of your table:

mysql> CREATE TABLE pet (name VARCHAR(20), owner VARCHAR(20),
    -> species VARCHAR(20), sex CHAR(1), birth DATE, death DATE);

VARCHAR is a good choice for the
name, owner, and
species columns because the column values
vary in length. The lengths in those column definitions need not
all be the same, and need not be 20. You can
normally pick any length from 1 to
65535, whatever seems most reasonable to you.

Note

Prior to MySQL 5.0.3, the upper limit was 255.) If you make a
poor choice and it turns out later that you need a longer
field, MySQL provides an ALTER TABLE
statement.

Several types of values can be chosen to represent sex in animal
records, such as 'm' and
'f', or perhaps 'male' and
'female'. It is simplest to use the single
characters 'm' and 'f'.

The use of the DATE data type for the
birth and death columns is
a fairly obvious choice.

Once you have created a table, SHOW TABLES

should produce some output:

mysql> SHOW TABLES;
+---------------------+
| Tables in menagerie |
+---------------------+
| pet                 |
+---------------------+

To verify that your table was created the way you expected, use
a DESCRIBE statement:

mysql> DESCRIBE pet;

+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| name    | varchar(20) | YES  |     | NULL    |       |
| owner   | varchar(20) | YES  |     | NULL    |       |
| species | varchar(20) | YES  |     | NULL    |       |
| sex     | char(1)     | YES  |     | NULL    |       |
| birth   | date        | YES  |     | NULL    |       |
| death   | date        | YES  |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+

You can use DESCRIBE any time, for example,
if you forget the names of the columns in your table or what
types they have.
Top

3. Loading Data into a Table

After creating your table, you need to populate it. The
LOAD DATA and INSERT
statements are useful for this.

Suppose that your pet records can be described as shown here.
(Observe that MySQL expects dates in
'YYYY-MM-DD' format; this may be different
from what you are used to.)

name	owner	species	sex	birth	death
Fluffy	Harold	cat	f	1993-02-04
Claws	Gwen	cat	m	1994-03-17
Buffy	Harold	dog	f	1989-05-13
Fang	Benny	dog	m	1990-08-27
Bowser	Diane	dog	m	1979-08-31	1995-07-29
Chirpy	Gwen	bird	f	1998-09-11
Whistler	Gwen	bird		1997-12-09
Slim	Benny	snake	m	1996-04-29

Because you are beginning with an empty table, an easy way to
populate it is to create a text file containing a row for each
of your animals, then load the contents of the file into the
table with a single statement.

You could create a text file pet.txt

containing one record per line, with values separated by tabs,
and given in the order in which the columns were listed in the
CREATE TABLE statement. For missing values
(such as unknown sexes or death dates for animals that are still
living), you can use NULL values. To
represent these in your text file, use \N
(backslash, capital-N). For example, the record for Whistler the
bird would look like this (where the whitespace between values
is a single tab character):

Whistler        Gwen    bird    \N      1997-12-09      \N

To load the text file pet.txt into the
pet table, use this command:

mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet;

Note that if you created the file on Windows with an editor that
uses \r\n as a line terminator, you should
use:

mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet
    -> LINES TERMINATED BY '\r\n';

(On an Apple machine running OS X, you would likely want to use
LINES TERMINATED BY '\r'.)

You can specify the column value separator and end of line
marker explicitly in the LOAD DATA statement
if you wish, but the defaults are tab and linefeed. These are
sufficient for the statement to read the file
pet.txt properly.

If the statement fails, it is likely that your MySQL
installation does not have local file capability enabled by
default. See Section 5.3.4, “Security Issues with LOAD DATA LOCAL”, for information
on how to change this.

When you want to add new records one at a time, the
INSERT statement is useful. In its simplest
form, you supply values for each column, in the order in which
the columns were listed in the CREATE TABLE

statement. Suppose that Diane gets a new hamster named
“Puffball.” You could add a new record using an
INSERT statement like this:

mysql> INSERT INTO pet
    -> VALUES ('Puffball','Diane','hamster','f','1999-03-30',NULL);

Note that string and date values are specified as quoted strings
here. Also, with INSERT, you can insert
NULL directly to represent a missing value.
You do not use \N like you do with
LOAD DATA.

From this example, you should be able to see that there would be
a lot more typing involved to load your records initially using
several INSERT statements rather than a
single LOAD DATA statement.
Top

MySql Tutorial 2 - Entering Queries

Make sure that you are connected to the server, as discussed in the previous section. Doing so does not in itself select any database to work with, but that's okay. At this point, it's more important to find out a little about how to issue queries than to jump right in creating tables, loading data into them, and retrieving data from them. This section describes the basic principles of entering commands, using several queries you can try out to familiarize yourself with how mysql works.

Here's a simple command that asks the server to tell you its version number and the current date. Type it in as shown here following the mysql> prompt and press Enter:

mysql> SELECT VERSION(), CURRENT_DATE;
+----------------+--------------+
| VERSION()      | CURRENT_DATE |
+----------------+--------------+
| 5.0.7-beta-Max | 2005-07-11   |
+----------------+--------------+
1 row in set (0.01 sec)
mysql>

This query illustrates several things about
mysql:

A command normally consists of an SQL statement followed by a semicolon. (There are some exceptions where a semicolon may be omitted. QUIT, mentioned earlier, is one of them. We'll get to others later.)

When you issue a command, mysql sends it to the server for execution and displays the results, then prints another mysql> prompt to indicate that it is ready for another command.

mysql displays query output in tabular form (rows and columns). The first row contains labels for the columns. The rows following are the query results. Normally, column labels are the names of the columns you fetch from database tables. If you're retrieving the value of an expression rather than a table column (as in the example just shown), mysql labels the column using the expression itself.

mysql shows how many rows were returned and how long the query took to execute, which gives you a rough idea of server performance. These values are imprecise because they represent wall clock time (not CPU or machine time), and because they are affected by factors such as server load and network latency. (For brevity, the “rows in set” line is sometimes not shown in the remaining examples in this chapter.)

Keywords may be entered in any lettercase. The following queries are equivalent:

mysql> SELECT VERSION(), CURRENT_DATE;

mysql> select version(), current_date;
mysql> SeLeCt vErSiOn(), current_DATE;

Here's another query. It demonstrates that you can use
mysql as a simple calculator:

mysql> SELECT SIN(PI()/4), (4+1)*5;

+------------------+---------+
| SIN(PI()/4)      | (4+1)*5 |
+------------------+---------+
| 0.70710678118655 |      25 |
+------------------+---------+
1 row in set (0.02 sec)

The queries shown thus far have been relatively short, single-line statements. You can even enter multiple statements on a single line. Just end each one with a semicolon:

mysql> SELECT VERSION(); SELECT NOW();
+----------------+
| VERSION()      |
+----------------+
| 5.0.7-beta-Max |
+----------------+
1 row in set (0.00 sec)

+---------------------+
| NOW()               |
+---------------------+
| 2005-07-11 17:59:36 |
+---------------------+  
1 row in set (0.00 sec)

A command need not be given all on a single line, so lengthy commands that require several lines are not a problem. mysql determines where your statement ends by looking for the terminating semicolon, not by looking for the end of the input line. (In other words, mysql accepts free-format input: it collects input lines but does not execute them until it sees the semicolon.)

Here's a simple multiple-line statement:

mysql> SELECT
    -> USER()
    -> ,

    -> CURRENT_DATE;
+---------------+--------------+
| USER()        | CURRENT_DATE |
+---------------+--------------+
| jon@localhost | 2005-07-11   |
+---------------+--------------+

In this example, notice how the prompt changes from mysql> to -> after you enter the first line of a multiple-line query. This is how mysql indicates that it has not yet seen a complete statement and is waiting for the rest. The prompt is your friend, because it provides valuable feedback. If you use that feedback, you can always be aware of what mysql is waiting for.

If you decide you do not want to execute a command that you are in the process of entering, cancel it by typing
\c:

mysql> SELECT
    -> USER()

    -> \c
mysql>

Here, too, notice the prompt. It switches back to mysql> after you type \c, providing feedback to indicate that mysql is ready for a new command.

The following table shows each of the prompts you may see and summarizes what they mean about the state that mysql is in:

Prompt	Meaning
`mysql>`	Ready for new command.
`->`	Waiting for next line of multiple-line command.
`'>`	Waiting for next line, waiting for completion of a string that began with a single quote (“`'`”).
`">`	Waiting for next line, waiting for completion of a string that began with a double quote (“`"`”).
`>	Waiting for next line, waiting for completion of an identifier that began with a backtick (“`”).
`/*>`	Waiting for next line, waiting for completion of a comment that began with `/*`.

In the MySQL 5.0 series, the /*> prompt was implemented in MySQL 5.0.6.

Multiple-line statements commonly occur by accident when you intend to issue a command on a single line, but forget the terminating semicolon. In this case, mysql waits for more input:

mysql> SELECT USER()

   ->

If this happens to you (you think you've entered a statement but the only response is a -> prompt), most likely mysql is waiting for the semicolon. If you don't notice what the prompt is telling you, you might sit there for a while before realizing what you need to do. Enter a semicolon to complete the statement, and mysql executes it:

mysql> SELECT USER()

   -> ;

+---------------+
| USER()        |
+---------------+
| jon@localhost |
+---------------+

The '> and "> prompts occur during string collection (another way of saying that MySQL is waiting for completion of a string). In MySQL, you can write strings surrounded by either “'” or “"” characters (for example, 'hello' or "goodbye"), and mysql lets you enter strings that span multiple lines. When you see a '> or "> prompt, it means that you have entered a line containing a string that begins with a “'” or “"” quote character, but have not yet entered the matching quote that terminates the string. This often indicates that you have inadvertently left out a quote character. For example:

mysql> SELECT * FROM my_table WHERE name = 'Smith AND age < 30;'>

If you enter this SELECT statement, then press Enter and wait for the result, nothing happens. Instead of wondering why this query takes so long, notice the clue provided by the '> prompt. It tells you that mysql expects to see the rest of an unterminated string. (Do you see the error in the statement? The string 'Smith is missing the second single quote mark.)

At this point, what do you do? The simplest thing is to cancel the command. However, you cannot just type \c in this case, because mysql interprets it as part of the string that it is collecting. Instead, enter the closing quote character (so mysql knows you've finished the string), then type \c:

mysql> SELECT * FROM my_table WHERE name = 'Smith AND age < 30;'> '\cmysql>

The prompt changes back to mysql>, indicating that mysql is ready for a new command.

The `> prompt is similar to the '> and "> prompts, but indicates that you have begun but not completed a backtick-quoted identifier.

It is important to know what the '>, ">, and `> prompts signify, because if you mistakenly enter an unterminated string, any further lines you type appear to be ignored by mysql — including a line containing QUIT. This can be quite confusing, especially if you do not know that you need to supply the terminating quote before you can cancel the current command.

MySql Tutorial 1 – Connecting to and Disconnecting from the Server

To connect to the server, you will usually need to provide a MySQL user name when you invoke mysql and, most likely, a password. If the server runs on a machine other than the one where you log in, you will also need to specify a host name. Contact your administrator to find out what connection parametersyou should use to connect (that is, what host, user name, and password to use). Once you know the proper parameters, you should be able to connect like this:

shell> mysql -h host -u user -p

Enter password: ********

host and user represent the
host name where your MySQL server is running and the user name of your MySQL account. Substitute appropriate values for your setup.
The ******** represents your password; enter it when mysql displays the Enter password: prompt.

If that works, you should see some introductory information followed by a mysql> prompt:

shell> mysql -h host -u user -p

Enter password: ********
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 25338 to server version: 5.0.56-standard

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>

The mysql> prompt tells you that mysql is ready for you to enter commands.

If you are logging in on the same machine that MySQL is running on, you can omit the host, and simply use the following:

shell> mysql -u user -p

If, when you attempt to log in, you get an error message such as ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2), it means that that MySQL server daemon (Unix) or service (Windows) is not running. Consult the administrator or see the section of Chapter 2, Installing and Upgrading MySQL that is appropriate to your operating system.

For help with other problems often encountered when trying to login, see Section B.1.2, “Common Errors When Using MySQL Programs”.

Some MySQL installations allow users to connect as the anonymous(unnamed) user to the server running on the local host. If this isthe case on your machine, you should be able to connect to that server by invoking mysql without any options:

shell> mysql

After you have connected successfully, you can disconnect any time by typing QUIT (or \q) at the mysql> prompt:

mysql> QUIT

Bye

On Unix, you can also disconnect by pressing Control-D.

Most examples in the following sections assume that you are connected to the server. They indicate this by the mysql> prompt.

PHP Filter

PHP filters are used to validate and filter data coming from insecure sources, like user input.

What is a PHP Filter?

A PHP filter is used to validate and filter data coming from insecure sources.

To test, validate and filter user input or custom data is an important part of any web application.

The PHP filter extension is designed to make data filtering easier and quicker.

Why use a Filter?

Almost all web applications depend on external input. Usually this comes from a user or another application (like a web service). By using filters you can be sure your application gets the correct input type.

You should always filter all external data!

Input filtering is one of the most important application security issues.

What is external data?

Input data from a form

Web services data

Server variables

Database query results

Functions and Filters

To filter a variable, use one of the following filter functions:

filter_var() - Filters a single variable with a specified filter

filter_var_array() - Filter several variables with the same or different
filters

filter_input - Get one input variable and filter it

filter_input_array - Get several input variables and filter them with
the same or different filters

In the example below, we validate an integer using the filter_var() function:

$int = 123;

if(!filter_var($int, FILTER_VALIDATE_INT))
 {
 echo("Integer is not valid");
 }
else
 {
 echo("Integer is valid");
 }
?>

The code above uses the "FILTER_VALIDATE_INT" filter to filter the variable. Since the integer is valid, the output of the code above will be:
"Integer is valid".

If we try with a variable that is not an integer (like "123abc"), the output will be: "Integer is not valid".

Validating and Sanitizing

There are two kinds of filters:

Validating filters:

Are used to validate user input

Strict format rules (like URL or E-Mail validating)

Returns the expected type on success or FALSE on failure

Sanitizing filters:

Are used to allow or disallow specified characters in a string

No data format rules

Always return the string

Options and Flags

Options and flags are used to add additional filtering options to the specified filters.

Different filters have different options and flags.

In the example below, we validate an integer using the filter_var() and the "min_range" and "max_range" options:

$var=300;

$int_options = array(
"options"=>array
 (
 "min_range"=>0,
 "max_range"=>256
 )
);

if(!filter_var($var, FILTER_VALIDATE_INT, $int_options))
 {
 echo("Integer is not valid");
 }
else
 {
 echo("Integer is valid");
 }
?>

Like the code above, options must be put in an associative array with the name "options". If a flag is used it does not need to be in an array.

Since the integer is "300" it is not in the specified range, and the output of the code above will be:
"Integer is not valid".

Validate Input

Let's try validating input from a form.

The first thing we need to do is to confirm that the input data we are
looking for exists.

Then we filter the input data using the filter_input() function.

In the example below, the input variable "email" is sent to the PHP page:

if(!filter_has_var(INPUT_GET, "email"))
 {
 echo("Input type does not exist");
 }
else
 {
 if (!filter_input(INPUT_GET, "email", FILTER_VALIDATE_EMAIL))
 {
 echo "E-Mail is not valid";
 }
 else
 {
 echo "E-Mail is valid";
 }
 }
?>

Example Explained

The example above has an input (email) sent to it using the "GET" method:

Check if an "email" input variable of the "GET" type exist

If the input variable exists, check if it is a valid e-mail address

Sanitize Input

Let's try cleaning up an URL sent from a form.

First we confirm that the input data we are looking for exists.

Then we sanitize the input data using the filter_input() function.

In the example below, the input variable "url" is sent to the PHP page:

if(!filter_has_var(INPUT_POST, "url"))
 {
 echo("Input type does not exist");
 }
else
 {
 $url = filter_input(INPUT_POST, 
 "url", FILTER_SANITIZE_URL);
 }
?>

Example Explained

The example above has an input (url) sent to it using the "POST" method:

Check if the "url" input of the "POST" type exists

If the input variable exists, sanitize (take away invalid characters) and store it in the $url variable

If the input variable is a string like this "http://www.iwebgator.com/", the $url variable after the sanitizing will look like this:

http://www.iwebgator.com/

Filter Multiple Inputs

A form almost always consist of more than one input field. To avoid calling the filter_var or filter_input functions over and over, we can use the filter_var_array or the filter_input_array functions.

In this example we use the filter_input_array() function to filter three GET variables. The received GET variables is a name, an age and an e-mail address:

$filters = array
 (
 "name" => array
 (
 "filter"=>FILTER_SANITIZE_STRING
 ),
 "age" => array
 (
 "filter"=>FILTER_VALIDATE_INT,
 "options"=>array
 (
 "min_range"=>1,
 "max_range"=>120
 )
 ),
 "email"=> FILTER_VALIDATE_EMAIL,
 );

$result = filter_input_array(INPUT_GET, $filters);

if (!$result["age"])
 {
 echo("Age must be a number between 1 and 120.
");
 }
elseif(!$result["email"])
 {
 echo("E-Mail is not valid.
");
 }
else
 {
 echo("User input is valid");
 }
?>

Example Explained

The example above has three inputs (name, age and email) sent to it using the "GET" method:

Set an array containing the name of input variables and the filters used on the specified input variables

Call the filter_input_array() function with the GET input variables and the array we just set

Check the "age" and "email" variables in the $result variable for invalid inputs. (If any of the input variables are invalid, that input variable will be FALSE after the filter_input_array() function)

The second parameter of the filter_input_array() function can be an array or
a single filter ID.

If the parameter is a single filter ID all values in the input array are
filtered by the specified filter.

If the parameter is an array it must follow these rules:

Must be an associative array containing an input variable as an array key (like the "age" input variable)

The array value must be a filter ID or an array specifying the filter, flags and options

Using Filter Callback

It is possible to call a user defined function and use it as a filter using the FILTER_CALLBACK filter. This way, we have full control of the data filtering.

You can create your own user defined function or use an existing PHP function

The function you wish to use to filter is specified the same way as an option is specified. In an associative array with the name "options"

In the example below, we use a user created function to convert all "_" to whitespaces:

function convertSpace($string)
{
return str_replace("_", " ", $string);
}

$string = "Peter_is_a_great_guy!";

echo filter_var($string, FILTER_CALLBACK,
array("options"=>"convertSpace"));
?>

The result from the code above should look like this:

Peter is a great guy!

Example Explained

The example above converts all "_" to whitespaces:

Create a function to replace "_" to whitespaces

Call the filter_var() function with the FILTER_CALLBACK filter and an array containing our function

PHP Exception Handling

Exceptions are used to change the normal flow of a script if a specified error occurs

What is an Exception

With PHP 5 came a new object oriented way of dealing with errors.

Exception handling is used to change the normal flow of the code execution if a specified error (exceptional) condition occurs. This condition is called an exception.

This is what normally happens when an exception is triggered:

The current code state is saved

The code execution will switch to a predefined (custom) exception handler function

Depending on the situation, the handler may then resume the execution from the saved code state, terminate the script execution or continue the script from a different location in the code

We will show different error handling methods:

Basic use of Exceptions

Creating a custom exception handler

Multiple exceptions

Re-throwing an exception

Setting a top level exception handler

Note: Exceptions should only be used with error conditions, and should not be used to jump to another place in the code at a specified point.

Basic Use of Exceptions

When an exception is thrown, the code following it will not be executed, and PHP will try to find the matching "catch" block.

If an exception is not caught, a fatal error will be issued with an "Uncaught Exception" message.

Lets try to throw an exception without catching it:

//create function with an exception
function checkNum($number)
 {
 if($number>1)
 {
 throw new Exception("Value must be 1 or below");
 }
 return true;
 }

//trigger exception
checkNum(2);
?>

The code above will get an error like this:

Fatal error: Uncaught exception 'Exception' 
with message 'Value must be 1 or below' in C:\webfolder\test.php:6 
Stack trace: #0 C:\webfolder\test.php(12): 
checkNum(28) #1 {main} thrown in C:\webfolder\test.php on line 6

Try, throw and catch

To avoid the error from the example above, we need to create the proper code to handle an exception.

Proper exception code should include:

Try - A function using an exception should be in a "try" block. If the exception does not trigger, the code will continue as normal. However if the exception triggers, an exception is "thrown"

Throw - This is how you trigger an exception. Each "throw" must have at least one "catch"

Catch - A "catch" block retrieves an exception and creates an object containing the exception information

Lets try to trigger an exception with valid code:

//create function with an exception
function checkNum($number)
 {
 if($number>1)
 {
 throw new Exception("Value must be 1 or below");
 }
 return true;
 }

//trigger exception in a "try" block
try
 {
 checkNum(2);
 //If the exception is thrown, this text will not be shown
 echo 'If you see this, the number is 1 or below';
 }

//catch exception
catch(Exception $e)
 {
 echo 'Message: ' .$e->getMessage();
 }
?>

The code above will get an error like this:

Message: Value must be 1 or below

Example explained:

The code above throws an exception and catches it:

The checkNum() function is created. It checks if a number is greater than 1. If it is, an exception is thrown

The checkNum() function is called in a "try" block

The exception within the checkNum() function is thrown

The "catch" block retrives the exception and creates an object ($e) containing the exception information

The error message from the exception is echoed by calling $e->getMessage() from the exception object

However, one way to get around the "every throw must have a catch" rule is to set a top level exception handler to handle errors that slip through.

Creating a Custom Exception Class

Creating a custom exception handler is quite simple. We simply create a special class with functions that can be called when an exception occurs in PHP. The class must be an extension of the exception class.

The custom exception class inherits the properties from PHP's exception class and you can add custom functions to it.

Lets create an exception class:

class customException extends Exception
 {
 public function errorMessage()
 {
 //error message
 $errorMsg = 'Error on line '.$this->getLine().' in '.$this->getFile()
 .': '.$this->getMessage().' is not a valid E-Mail address';
 return $errorMsg;
 }
 }

$email = "someone@example...com";

try
 {
 //check if 
 if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE)
 {
 //throw exception if email is not valid
 throw new customException($email);
 }
 }

catch (customException $e)
 {
 //display custom message
 echo $e->errorMessage();
 }
?>

The new class is a copy of the old exception class with an addition of the errorMessage() function. Since it is a copy of the old class, and it inherits the properties and methods from the old class, we can use the exception class methods like getLine() and getFile() and getMessage().

Example explained:

The code above throws an exception and catches it with a custom exception class:

The customException() class is created as an extension of the old exception class. This way it inherits all methods and properties from the old exception class

The errorMessage() function is created. This function returns an error message if an e-mail address is invalid

The $email variable is set to a string that is not a valid e-mail address

The "try" block is executed and an exception is thrown since the e-mail address is invalid

The "catch" block catches the exception and displays the error message

Multiple Exceptions

It is possible for a script to use multiple exceptions to check for multiple conditions.

It is possible to use several if..else blocks, a switch, or nest multiple exceptions. These exceptions can use different exception classes and return different error messages:

class customException extends Exception
{
public function errorMessage()
{
//error message
$errorMsg = 'Error on line '.$this->getLine().' in '.$this->getFile()
.': '.$this->getMessage().' is not a valid E-Mail address';
return $errorMsg;
}
}

$email = "someone@example.com";

try
 {
 //check if 
 if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE)
 {
 //throw exception if email is not valid
 throw new customException($email);
 }
 //check for "example" in mail address
 if(strpos($email, "example") !== FALSE)
 {
 throw new Exception("$email is an example e-mail");
 }
 }

catch (customException $e)
 {
 echo $e->errorMessage();
 }

catch(Exception $e)
 {
 echo $e->getMessage();
 }
?>

Example explained:

The code above tests two conditions and throws an exception if any of the conditions are not met:

The customException() class is created as an extension of the old exception class. This way it inherits all methods and properties from the old exception class

The errorMessage() function is created. This function returns an error message if an e-mail address is invalid

The $email variable is set to a string that is a valid e-mail address, but contains the string "example"

The "try" block is executed and an exception is not thrown on the first condition

The second condition triggers an exception since the e-mail contains the string "example"

The "catch" block catches the exception and displays the correct error message

If there was no customException catch, only the base exception catch, the exception would be handled there

Re-throwing Exceptions

Sometimes, when an exception is thrown, you may wish to handle it differently than the standard way. It is possible to throw an exception a second time within a "catch" block.

A script should hide system errors from users. System errors may be important for the coder, but is of no interest to the user. To make things easier for the user you can re-throw the exception with a user friendly message:

class customException extends Exception
 {
 public function errorMessage()
 {
 //error message
 $errorMsg = $this->getMessage().' is not a valid E-Mail address.';
 return $errorMsg;
 }
 }

$email = "someone@example.com";

try
 {
 try
 {
 //check for "example" in mail address
 if(strpos($email, "example") !== FALSE)
 {
 //throw exception if email is not valid
 throw new Exception($email);
 }
 }
 catch(Exception $e)
 {
 //re-throw exception
 throw new customException($email);
 }
 }

catch (customException $e)
 {
 //display custom message
 echo $e->errorMessage();
 }
?>

Example explained:

The code above tests if the email-address contains the string "example" in
it, if it does, the exception is re-thrown:

The customException() class is created as an extension of the old exception class. This way it inherits all methods and properties from the old exception class

The errorMessage() function is created. This function returns an error message if an e-mail address is invalid

The $email variable is set to a string that is a valid e-mail address, but contains the string "example"

The "try" block contains another "try" block to make it possible to re-throw the exception

The exception is triggered since the e-mail contains the string "example"

The "catch" block catches the exception and re-throws a "customException"

The "customException" is caught and displays an error message

If the exception is not caught in it's current "try" block, it will search for a catch block on "higher levels".

Set a Top Level Exception Handler

The set_exception_handler() function sets a user-defined function to handle all uncaught exceptions.

function myException($exception)
{
echo "Exception: " , $exception->getMessage();
}

set_exception_handler('myException');

throw new Exception('Uncaught Exception occurred');
?>

The output of the code above should be something like this:

Exception: Uncaught Exception occurred

In the code above there was no "catch" block. Instead, the top level exception handler triggered. This function should be used to catch uncaught exceptions.

Rules for exceptions

Code may be surrounded in a try block, to help catch potential exceptions

Each try block or "throw" must have at least one corresponding catch block

Multiple catch blocks can be used to catch different classes of exceptions

Exceptions can be thrown (or re-thrown) in a catch block within a try block

A simple rule: If you throw something, you have to catch it.

PHP Error Handling

The default error handling in PHP is very simple. An error message with filename, line number and a message describing the error is sent to the browser.

PHP Error Handling

When creating scripts and web applications, error handling is an important part. If your code lacks error checking code, your program may look very unprofessional and you may be open to security risks.

This tutorial contains some of the most common error checking methods in PHP.

We will show different error handling methods:

Simple "die()" statements

Custom errors and error triggers

Error reporting

Basic Error Handling: Using the die() function

The first example shows a simple script that opens a text file:

$file=fopen("welcome.txt","r");
?>

If the file does not exist you might get an error like this:

Warning: fopen(welcome.txt) [function.fopen]: failed to open stream: 
No such file or directory in C:\webfolder\test.php on line 2

To avoid that the user gets an error message like the one above, we test if the file exist before we try to access it:

if(!file_exists("welcome.txt"))
 {
 die("File not found");
 }
else
 {
 $file=fopen("welcome.txt","r");
 }
?>

Now if the file does not exist you get an error like this:

File not found

The code above is more efficient than the earlier code, because it uses a simple error handling mechanism to stop the script after the error.

However, simply stopping the script is not always the right way to go. Let's take a look at alternative PHP functions for handling errors.

Creating a Custom Error Handler

Creating a custom error handler is quite simple. We simply create a special function that can be called when an error occurs in PHP.

This function must be able to handle a minimum of two parameters (error level and error message) but can accept up to five parameters (optionally: file, line-number, and the error context):

Syntax

error_function(error_level,error_message,
error_file,error_line,error_context)

Parameter	Description
error_level	Required. Specifies the error report level for the user-defined error. Must be a value number. See table below for possible error report levels
error_message	Required. Specifies the error message for the user-defined error
error_file	Optional. Specifies the filename in which the error occurred
error_line	Optional. Specifies the line number in which the error occurred
error_context	Optional. Specifies an array containing every variable, and their values, in use when the error occurred

Error Report levels

These error report levels are the different types of error the user-defined error handler can be used for:

Value	Constant	Description
2	E_WARNING	Non-fatal run-time errors. Execution of the script is not halted
8	E_NOTICE	Run-time notices. The script found something that might be an error, but could also happen when running a script normally
256	E_USER_ERROR	Fatal user-generated error. This is like an E_ERROR set by the programmer using the PHP function trigger_error()
512	E_USER_WARNING	Non-fatal user-generated warning. This is like an E_WARNING set by the programmer using the PHP function trigger_error()
1024	E_USER_NOTICE	User-generated notice. This is like an E_NOTICE set by the programmer using the PHP function trigger_error()
4096	E_RECOVERABLE_ERROR	Catchable fatal error. This is like an E_ERROR but can be caught by a user defined handle (see also set_error_handler())
8191	E_ALL	All errors and warnings, except level E_STRICT (E_STRICT will be part of E_ALL as of PHP 6.0)

Now lets create a function to handle errors:

function customError($errno, $errstr)
 { 
 echo "Error: [$errno] $errstr
";
 echo "Ending Script";
 die();
 }

The code above is a simple error handling function. When it is triggered, it gets the error level and an error message. It then outputs the error level and message and terminates the script.

Now that we have created an error handling function we need to decide when it should be triggered.

Set Error Handler

The default error handler for PHP is the built in error handler. We are going to make the function above the default error handler for the duration of the script.

It is possible to change the error handler to apply for only some errors, that way the script can handle different errors in different ways. However, in this example we are going to use our custom error handler for all errors:

set_error_handler("customError");

Since we want our custom function to handle all errors, the set_error_handler() only needed one parameter, a second parameter could be added to specify an error level.

Example

Testing the error handler by trying to output variable that does not exist:

//error handler function
function customError($errno, $errstr)
 { 
 echo "Error: [$errno] $errstr";
 }

//set error handler
set_error_handler("customError");

//trigger error
echo($test);
?>

The output of the code above should be something like this:

Custom error: [8] Undefined variable: test

Trigger an Error

In a script where users can input data it is useful to trigger errors when an illegal input occurs. In PHP, this is done by the trigger_error() function.

Example

In this example an error occurs if the "test" variable is bigger than "1":

$test=2;
if ($test>1)
{
trigger_error("Value must be 1 or below");
}
?>

The output of the code above should be something like this:

Notice: Value must be 1 or below
in C:\webfolder\test.php on line 6

An error can be triggered anywhere you wish in a script, and by adding a second parameter, you can specify what error level is triggered.

Possible error types:

E_USER_ERROR - Fatal user-generated run-time error. Errors that can not be recovered from. Execution of the script is halted

E_USER_WARNING - Non-fatal user-generated run-time warning. Execution of the script is not halted

E_USER_NOTICE - Default. User-generated run-time notice. The script found something that might be an error, but could also happen when running a script normally

Example

In this example an E_USER_WARNING occurs if the "test" variable is bigger than "1". If an E_USER_WARNING occurs we will use our custom error handler and end the script:

//error handler function
function customError($errno, $errstr)
 { 
 echo "Error: [$errno] $errstr
";
 echo "Ending Script";
 die();
 }

//set error handler
set_error_handler("customError",E_USER_WARNING);

//trigger error
$test=2;
if ($test>1)
 {
 trigger_error("Value must be 1 or below",E_USER_WARNING);
 }
?>

The output of the code above should be something like this:

Error: [512] Value must be 1 or below
Ending Script

Now that we have learned to create our own errors and how to trigger them, lets take a look at error logging.

Error Logging

By default, PHP sends an error log to the servers logging system or a file, depending on how the error_log configuration is set in the php.ini file. By using the error_log() function you can send error logs to a specified file or a remote destination.

Sending errors messages to yourself by e-mail can be a good way of getting notified of specific errors.

Send an Error Message by E-Mail

In the example below we will send an e-mail with an error message and end the script, if a specific error occurs:

//error handler function
function customError($errno, $errstr)
 { 
 echo "Error: [$errno] $errstr
";
 echo "Webmaster has been notified";
 error_log("Error: [$errno] $errstr",1,
 "someone@example.com","From: webmaster@example.com");
}

//set error handler
set_error_handler("customError",E_USER_WARNING);

//trigger error
$test=2;
if ($test>1)
 {
 trigger_error("Value must be 1 or below",E_USER_WARNING);
 }
?>

The output of the code above should be something like this:

Error: [512] Value must be 1 or below
Webmaster has been notified

And the mail received from the code above looks like this:

Error: [512] Value must be 1 or below

This should not be used with all errors. Regular errors should be logged on the server using the default PHP logging system.

PHP Secure E-mails

There is a weakness in the PHP e-mail script in the previous chapter.

PHP E-mail Injections

First, look at the PHP code from the previous chapter:

if (isset($_REQUEST['email']))
//if "email" is filled out, send email
 {
 //send email
 $email = $_REQUEST['email'] ; 
 $subject = $_REQUEST['subject'] ;
 $message = $_REQUEST['message'] ;
 mail("someone@example.com", "Subject: $subject",
 $message, "From: $email" );
 echo "Thank you for using our mail form";
 }
else
//if "email" is not filled out, display the form
 {
 echo "
 Email: 


 Subject: 

 Message:

 <br /> 

 

 
";
 }
?>

The problem with the code above is that unauthorized users can insert data into the
mail headers via the input form.

What happens if the user adds the following text to the email input field in
the form?

someone@example.com%0ACc:person2@example.com
%0ABcc:person3@example.com,person3@example.com,
anotherperson4@example.com,person5@example.com
%0ABTo:person6@example.com

The mail() function puts the text above into the mail headers as usual, and now the
header has an extra Cc:, Bcc:, and To: field. When the user clicks the submit
button, the e-mail will be sent to all of the addresses above!

PHP Stopping E-mail Injections

The best way to stop e-mail injections is to validate the input.

The code below is the same as in the previous chapter, but now we have added an input validator
that checks the email field in the form:



function spamcheck($field)
 {
 //filter_var() sanitizes the e-mail 
 //address using FILTER_SANITIZE_EMAIL
 $field=filter_var($field, FILTER_SANITIZE_EMAIL);
 
 //filter_var() validates the e-mail
 //address using FILTER_VALIDATE_EMAIL
 if(filter_var($field, FILTER_VALIDATE_EMAIL))
  {
  return TRUE;
  }
 else
  {
  return FALSE;
  }
 }

if (isset($_REQUEST['email']))
 {//if "email" is filled out, proceed

 //check if the email address is invalid
 $mailcheck = spamcheck($_REQUEST['email']);
 if ($mailcheck==FALSE)
  {
  echo "Invalid input";
  }
 else
  {//send email
  $email = $_REQUEST['email'] ; 
  $subject = $_REQUEST['subject'] ;
  $message = $_REQUEST['message'] ;
  mail("someone@example.com", "Subject: $subject",
  $message, "From: $email" );
  echo "Thank you for using our mail form";
  }
 }
else
 {//if "email" is not filled out, display the form
 echo "

 Email: 

 Subject: 

 Message:

 <br /><br /> 

 
 
";
 }
?>

In the code above we use PHP filters to validate input:

The FILTER_SANITIZE_EMAIL filter removes all illegal e-mail characters
from a string

The FILTER_VALIDATE_EMAIL filter validates value as an e-mail address

The PHP mail() Function

PHP allows you to send e-mails directly from a script.

The PHP mail() Function

The PHP mail() function is used to send emails from inside a script.

Syntax

mail(to,subject,message,headers,parameters)

Parameter	Description
to	Required. Specifies the receiver / receivers of the email
subject	Required. Specifies the subject of the email. Note: This parameter cannot contain any newline characters
message	Required. Defines the message to be sent. Each line should be separated with a LF (\n). Lines should not exceed 70 characters
headers	Optional. Specifies additional headers, like From, Cc, and Bcc. The additional headers should be separated with a CRLF (\r\n)
parameters	Optional. Specifies an additional parameter to the sendmail program

Note: For the mail functions to be available, PHP requires an installed
and working email system. The program to be used is defined by the configuration
settings in the php.ini file. Read more in our PHP
Mail reference.

PHP Simple E-Mail

The simplest way to send an email with PHP is to send a text email.

In the example below we first declare the variables ($to, $subject, $message,
$from, $headers), then we use the variables in the mail() function to send an e-mail:


$to = "someone@example.com";
$subject = "Test mail";
$message = "Hello! This is a simple email message.";
$from = "someonelse@example.com";
$headers = "From: $from";
mail($to,$subject,$message,$headers);
echo "Mail Sent.";

?>

PHP Mail Form

With PHP, you can create a feedback-form on your website. The example below
sends a text message to a specified e-mail address:

if (isset($_REQUEST['email']))
//if "email" is filled out, send email
 {
 //send email
 $email = $_REQUEST['email'] ; 
 $subject = $_REQUEST['subject'] ;
 $message = $_REQUEST['message'] ;
 mail( "someone@example.com", "Subject: $subject",
 $message, "From: $email" );
 echo "Thank you for using our mail form";
 }
else
//if "email" is not filled out, display the form
 {
 echo "
 Email: 


 Subject: 

 Message:

 <br /> 

 

 
";
 }
?>

This is how the example above works:

First, check if the email input field is filled out

If it is not set (like when the page is
first visited); output the HTML form

If it is set (after the form is filled out);
send the email from the form

When submit is pressed after the form is filled out, the page reloads,
sees that the email input is set, and sends the email

Note: This is the simplest way to send e-mail, but it is not
secure. In the next chapter of this tutorial you can read more about vulnerabilities in e-mail
scripts, and how to validate user input to make it more secure.

PHP Session Variables

A PHP session variable is used to store information about, or change settings for a user session. Session variables hold information about one single user, and are available to all pages in one application.

PHP Session Variables

When you are working with an application, you open it, do some changes and then you close it. This is much like a Session. The computer knows who you are. It knows when you start the application and when you end. But on the internet there is one problem: the web server does not know who you are and what you do because the HTTP address doesn't maintain state.

A PHP session solves this problem by allowing you to store user information on the server for later use (i.e. username, shopping items, etc). However, session information is temporary and will be deleted after the user has left the website. If you need a permanent storage you may want to store the data in a database.

Sessions work by creating a unique id (UID) for each visitor and store variables based on this UID. The UID is either stored in a cookie or is propagated in the URL.

Starting a PHP Session

Before you can store user information in your PHP session, you must first start up the session.

Note: The session_start() function must appear BEFORE the tag:

The code above will register the user's session with the server, allow you to start saving user information, and assign a UID for that user's session.

Storing a Session Variable

The correct way to store and retrieve session variables is to use the PHP $_SESSION variable:

session_start();
// store session data
$_SESSION['views']=1;
?>

//retrieve session data
echo "Pageviews=". $_SESSION['views'];
?>

Output:

Pageviews=1

In the example below, we create a simple page-views counter. The isset() function checks if the "views" variable has already been set. If "views" has been set, we can increment our counter. If "views" doesn't exist, we create a "views" variable, and set it to 1:


session_start();

if(isset($_SESSION['views']))
 $_SESSION['views']=$_SESSION['views']+1;

else
 $_SESSION['views']=1;
echo "Views=". $_SESSION['views']; 
?>

Destroying a Session

If you wish to delete some session data, you can use the unset() or the session_destroy() function.

The unset() function is used to free the specified session variable:

unset($_SESSION['views']);
?>

You can also completely destroy the session by calling the session_destroy() function:

session_destroy();
?>

Note: session_destroy() will reset your session and you will lose all your stored session data.

Wednesday, July 7, 2010

Contents

Retrieving a Single Column

Using SELECT to Retrieve Mutiple Columns

Restricting Number of Results

Eliminating Duplicate Values from Results

Summary

1. Creating and Selecting a Database

Note

2. Creating a Table

Note

3. Loading Data into a Table

What is a PHP Filter?

Why use a Filter?

Functions and Filters

Validating and Sanitizing

Options and Flags

Validate Input

Example Explained

Sanitize Input

Example Explained

Filter Multiple Inputs

Example Explained

Using Filter Callback

Example Explained

What is an Exception

Basic Use of Exceptions

Try, throw and catch

Example explained:

Creating a Custom Exception Class

Example explained:

Multiple Exceptions

Example explained:

Re-throwing Exceptions

Example explained:

Set a Top Level Exception Handler

Rules for exceptions

PHP Error Handling

Basic Error Handling: Using the die() function

Creating a Custom Error Handler

Syntax

Error Report levels

Set Error Handler

Example

Trigger an Error

Example

Example

Error Logging

Send an Error Message by E-Mail

PHP E-mail Injections

PHP Stopping E-mail Injections

The PHP mail() Function

PHP Simple E-Mail

PHP Mail Form

PHP Session Variables

Starting a PHP Session

Storing a Session Variable

Destroying a Session

Subscribe by email

Search This Blog

Subscribe To

GET WIDGETS

PAGE RANK

RECENT POSTS

Recent Comments

Blog Archive

BlogRoll