PHP Summary

PHP stands for Hypertext Preprocessor and is a server-side scripting language.

PHP scripts should always be enclosed in between two PHP tags. This tells the server to parse all the information between them as PHP code. The three different ways for this are as follows:

• A variable name should always start with a letter or an underscore "_"
• A variable name only contains underscores and alpha-numeric characters (a-Z, 0-9, and _ )
• A variable name should not contain spaces in between. If the variable name should be of more than one word, it should be separated by underscore (like $my_string), or with capitalization ($myString)

• Assignment Operator
• Dot Operator
• Arithmetic Operators
• Comparison Operators

The include() function includes and evaluates the specified file. The include() statement takes all the contents of the specified file and copies it to the one which consist this statement.

Similarly the require() statement includes and evaluates the specified file. Both include() and require() works in same way, the only difference is how they handle failure. The include() statement produces warning, but the script will continue its execution. While the require() statement produces a Fatal Error and script stop its execution..

In a cookie there are information about a name, value, expiry date, host and path. As cookies are sent from server through HTTP header, they end up to the user. Here are the 3 ways to access cookies:

• using �$HTTP-COOKIE� which is the environmental variable, all cookie names and values are present in this variable.
• using global variable �$cookie_name�, here the name should be replaced
• using �HTTP_COOKIE_VARS [�cookie_name�]� which is a global array variable. (here replace the �cookie_name� by actual name of the cookie).

The main difference between sessions and cookies is that a session can hold multiple variables, and you need not have to set cookies for every variable. By default, the session data is stored in the cookie wich has an expiry date of zero, which means that the session remains active only as long as the browser.Once you close the browser, all the stored information is lost. This behavior can be modified by changing the �session. cookie_lifetime� setting in �php.ini� from zero to whatever you want the cookie lifetime to be.

we can summarize the process of accessing and working with a database connection from within a PHP script in the following steps.

• First you need to establish a connection to the database server.
• You should have to validate any user input
• Then select the database on the server to use.
• Execute all the desired query against the database.
• Furter retrieve and process the results.
• Then create HTML or perform actions based on results.
• Finally close the database connection.