MySQL only insert if there isn't an exact row in the Table

I need to insert this in a table but only if there isn't a replica of the row already. (both values should be equal). How can I change the code to work this way? Thanks

<?php
mysql_select_db("cyberworlddb", $con);
mysql开发者_开发技巧_query("INSERT INTO Badges (UID, Website)
VALUES ('1', 'www.taringa.net')");
mysql_close($con)
?>

You could create a single index for the UID and Website columns and make that index unique, then use INSERT IGNORE. The result will be that if it is a duplicate, it will just be ignored.

If you need to be able to tell if the SQL inserted a row, then follow it up with a call to mysql_affected_rows() which should return 0 if it didn't do anything and 1 if it inserted the record.

Easiest thing to do is use INSERT IGNORE and have a unique key on the fields. It will insert if no row exists, otherwise do nothing.

What about a unique index on (UID, Website), which would cause the insert to fail?

First up, about the question. It is simple bad to check for "an exact" replica of row in RDBMS. That is just too costly. The right question to ask is what makes my row unique and what is the minimum I can get away with. Putting in unique constraints on big columns is a bad idea.

Answers saying that you should include UID in unique constraint are again just BAD. UID is most likely a generated key and the only input coming from outside is website name. So the only sane thing to do here is to put a unique constraint on website column.

Then the insert code should handle unique constraint errors coming out from the database. You can get the error number from DB handle, like

$errorNo = $mysql->errno ; Then check for a particular code (1062 in case of MYSQL) that corresponds to unique key violation.