Query Help... AGAIN

[Anon]

I need MySQL query help (again). I am relatively new to SQL querying so here is my dilemma. I had a similiar problem, refer to <A HREF="http://phpbuilder.net/forum/archives/5/2001/07/2/15189">my other problem.</A>

I have 2 tables P2CLookup and Descriptions. P2CLookup has a product id and a category name. Descriptions has a product id and a description.

I want to formulate a query where it will retrieve all records that do not have a product id in P2CLookup nor in Descriptions. I have tried using left join but only returns NULL. I have 138 records in Descriptions but only 137 records in P2CLookup. I need to find out what product id is not in Descriptions. Any help would be greatly appreciated since I am struggling with advanced SQL concepts.

[[deleted]]

You were on the right track with the LEFT JOIN.

The trick is to LEFT JOIN the tables together, and find the rows where the right table gives you a NULL.

http://www.mysql.com/doc/J/O/JOIN.html
-- quote --
If there is no matching record for the right table in the ON or USING part in a LEFT JOIN, a row with all columns set to NULL is used for the right table. You
can use this fact to find records in a table that have no counterpart in another table:

 mysql> select table1.* from table1
            LEFT JOIN table2 ON table1.id=table2.id
            where table2.id is NULL;

-- end quote --