syntax of sprintf

until i started using the techniques for avoiding sql injection, i have been using a normal insert and select sql query which worked fine.

i have a registration page where a user enters their username and if this already exists i display a message by executing a select query and if the username does not exist then i run an insert query.

after adopting the technique to avoid sql injection

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

else
{
$username = $_POST["username"];
$email = $_POST["email"];
}
previously my select and insert query were

INSERT INTO individuals(username, email) values('$username', '$email')
Select username from individuals where username = '$username'

presently the insert query is

$insertquery = sprintf("INSERT INTO individuals (username, email) VALUES ('%s', '%s')",
mysql_real_escape_string($username), mysql_real_escape_string($email));

This insert query is working however the select query is not doing its task as before of checking if the username already exists or not, even if i register with the same username again it does not alert that the username exists.

the select query is

$selectqueryusername = sprintf("Select username from individuals where username='%s'", mysql_real_escape_string($username));

should i change the syntax of the above select query or is there something else in need to do to fix the select query.

also for insert query if i have a numeric value i should be writting %d correct, i have a numeric value however before inserting that numeric value i am appending a character "-" to combine area code and phone number example 09-123 4567 so i am considering this as %s as there is a character. is this correct.

please advice.

thanks.

 

Basically, sprintf can be used for many things, not only in mysql

$name = 'John';

$message = 'Hello, my name is %s. I live here';
$message = sprintf($message, $name);

$age = 15;

$message = 'Hello, i am %s years old. I live here';
$message = sprintf($message, $age);

PHP:

 

maybe there are some error in the previous step,you can print out $selectqueryusername to see what is the real query and see what happened.

You are correct, "09-123 4567" is a string,