Checking the existence of a database record

[engr]

i have a itemCode field which is the primary key but is entered by the user.
how do i check if the item code already exist to prevent error entry of the same itemCode?

[Huevoos]

neither MySql nor Postgress allow a duplicate primary key, so you should just check the affected rows http://www.php.net/manual/en/function.mysql-affected-rows.php after the insert, or you could do a simple "select itemCode from table where itemCode = $itemCode" before the insert or you could make a trigger, but that's more mysql related.

[engr]

found the solution!
$select="Select * from tblitem where ItemCode='$code'"; //here $code is the textbox containing the item code.
$res=mysql_query($select,$db);
if (mysql_num_rows($res)=0)
{

[engr]

found the solution!
$select="Select * from tblitem where ItemCode='$code'"; //here $code is the textbox containing the item code.
$res=mysql_query($select,$db);
if (mysql_num_rows($res)=0)
{
insert query
}
else
$msg="Item code already exists!";