Question

According to my previous Query that post i have a table that looks like this:

|| *nid* || *language* ||
|| 8 || Chinese ||
|| 8 || Portuguese ||
|| 8 || German |

In which ‘nid’ and ‘language’ have a unique constraint.

With this setup how can i make sure that the there wont be any duplicate when i try to insert a new row ?

EDITED

I am guessing I should try to make a query such as:

SELECT * FROM lang WHERE nid = $nid AND language = $lang

If this return FALSE then i know i can now insert my data. Is this correct ?

Answer 1

Enforce the unique constraint by creating a unique key:

ALTER TABLE the_table
ADD UNIQUE INDEX nid_language_unique (nid, language);

This constraint forbid two rows having the same nid and language.

Any query attempting to violate the constraint will fail.

As you want to ignore errors (and still abort the query), you can use INSERT IGNORE and UPDATE IGNORE:

INSERT IGNORE INTO the_table (nid, language) VALUES (8, 'Chinese')
/* row not inserted and no error */