sql injection

[runway27]

i have implemented a way to avoid sql injection from the php website from this url
http://in.php.net/mysql_real_escape_string from the "Example #3 A "Best Practice" query" section of this page

following are the steps i have followed after the form values are submitted to a php file.

step 1.

if(get_magic_quotes_gpc()) 
{
$username = stripslashes($_POST["username"]);
.........
}
 
else
{
$username = $_POST["username"];
.........
}
 

step 2.

$conn = mysql_connect($hostname, $user, $password);
 

step 3.

$insertquery = sprintf("INSERT INTO table (`username`, ...) VALUES ('%s', ...)", mysql_real_escape_string($username, $conn), 
 
...);
 

step 4.

    if(!$conn)
    { 
header("Location: http://website/dberror.html"); 
exit;
    }
 
    else
    {
mysql_select_db($database, $conn);
 
$insertqueryresult = mysql_query($insertquery);       
 
 
    if(!$insertqueryresult)    {        
    header("Location: http://website/error.html"); 
    exit;                     }     
 
    }
 

with the above method i am able to insert values into the table even with if i enter the ' special character which can cause

problems.

i have also used a simple sql insert query like

$insertquery = "INSERT INTO table(username, ...) VALUES ('$username', ...)";
 

when i used this simple insert query and if i entered ' in the form and submitted the form the php file is unable to process

the information entered because of the ' character and as per the code error.html file is being displayed where as if i use

$insertquery = sprintf("INSERT INTO table (`username`, ...) VALUES ('%s', ...)", mysql_real_escape_string($username, $conn), 
 
...);
 

even if i enter any number of ' characters in more than 1 form field data is being inserted into the table

a)
so i am thinking that the steps i have taken from the php site is correct and the right way to avoid sql injection though

there are several ways to avoid sql injection.

b)
for example if i enter data in the form as = abc'''def for name, the data in the table for the name field is being written as

abc'''def

based on how i have written the steps to avoid sql injection is this the right way for the data to be stored with '

characters along with the data example as i mentioned = abc'''def

please answer the questions a) and b) if there is something else i need to do please suggest what needs to be done exactly

and at which step.

any help will be greatly appreciated.

thanks.

[pbmods]

Heya, Runway.

mysql_real_esca pe_string() essentially escapes quotes and comment characters (such as -- and /*) by prepending them with slashes (e.g., "abc'''123" becomes "abc\'\'\'123") .

Since these characters can be changed (though very rarely are), mysql_real_esca pe_string() is preferred over addslashes() or addcslashes().

For maximum security and more organized code, you should consider switching to MySQLi and its ability to use prepared statements.