checking for a value in a table

I know what I want to do, don't know how exactly to go about it. Any help would be greatly appreciated.

I want to check a field for a certain value and return an answer in PHP so that I know whether or not to continue.

Example:

A user wants to register on the site. He goes to a register page, and it asks for his desired username, and a password. How can I check my table (say, TBLUSERS) for the name he entered, and return a true/false value, checking if someone already has that name?

Mike

Well, you can always MacGuyver up a while loop to check all the fields in the table, eg;
(this assumes you use odbc database, and the first field is where the username is stored)

<BLOCKQUOTE><font size="1" face="Verdana,Arial,Helvetica">code:</font><HR><pre>

while(odbc_fetch_row($cur)) {
$tmp = odbc_result($cur,1)
if ($tmp != $username) { $username_free = "FALSE"; break; } else { continue; }
}
$username_free = "TRUE";

[/code]

This loops through the table, checking the 'username' field. If it doesn't find a match, it sets the variable as 'true', otherwise it returns a 'false'.

Okay.. that might look like what I'm looking for... Can I do that with MySQL?

Mike

EGADS! Don't do THAT!

If the desired username is in $username:

$result=mysql_query("select count(*) from user_table where username='$username'");
if(mysql_num_rows($result))
{
// username already used
}else
{
// username available
}

That wasn't what I was looking for, however, I think that does the job and I understand what I'm doing there more.

Appreciate the help from both of ya!

Mike