PHP check unique record

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Added by amorph on May-15-2007, 4:01 pm

Function to check if a record that is supposed to be stored to db already exists or not.

3 comments Bury Details

BookmarkCategory: PHP

function checkUnique($table, $field, $compared)
{
	$query = mysql_query('SELECT  '.mysql_real_escape_string($field).' FROM '.mysql_real_escape_string($table).' WHERE "'.mysql_real_escape_string($field).'" = "'.mysql_real_escape_string($compared).'"');
	if(mysql_num_rows($query)==0)
	{
		return TRUE;
	}
	else {
		return FALSE;
	}
}

Comments

web2works says:I have had nothing but problem with this for the past few days managed to get it to work a moment ago through I would share my code: function checkUnique($table, $field, $compared) { $tablenew=mysql_real_escape_string($table); $fieldnew=mysql_real_escape_string($field); $comparednew=mysql_real_escape_string($compared); $query="SELECT $fieldnew FROM $tablenew WHERE $fieldnew='$comparednew'"; $result=mysql_query($query); $num=mysql_num_rows($result); if($num==0) { return TRUE; } else { return FALSE } } PHP validation: checkUnique('users', 'Email', $_POST['email'])==FALSE
2009-04-18 | 11:27 pm
skinner927@gmail.com says:I ran into the same problem. the query will return FALSE if it doesn't find anything. Add this right above the first if statement, and it should fix everything if(!$query){ return TRUE; }
2008-05-09 | 01:51 am
Big Talk says:Hello, I am really a noob. I used this function in the Login script. I ran into some problems when I tried to diversify the error messages in the registration form. I looked around and fixed this function to read: function checkUnique ($table, $field, $compared) { db_connect (); $query = mysql_query(' SELECT ' . mysql_real_escape_string($field) . ' FROM ' . mysql_real_escape_string($table) . ' WHERE "' . mysql_real_escape_string($field) . '" = "' . mysql_real_escape_string($compared) . '"'); if ($query == FALSE) { @mysql_close (); return TRUE; } else { @mysql_close (); return FALSE; } } The difference being that according to the PHP Manual, mysql_query () returns a resource or FALSE: For SELECT, SHOW, DESCRIBE, EXPLAIN and other statements returning resultset, mysql_query() returns a resource on success, or FALSE on error. The way it was being used in this function, it uses SELECT. $query will never really return 0. It will return a resource or FALSE. The idea is to check for uniqueness. So we still turn FALSE to TRUE, else: FALSE. That way it still can be "True" that something is unique. I hope this comment helps someone who may be struggling with what I struggled with! Also, If I have it wrong somehow, someone please correct me! I'm a noob! Happy coding!
2008-01-17 | 04:00 pm