Question

I have two tables which have some transactional stuff stored in them. There will be many records per user_id in each table. Table1 and Table2 have a one-to-one relationship with each other. I want to pull records from both tables, but I want to exclude records which have certain values in both tables. I don’t care if they both don’t have these values, or if just one does, but both tables should not have both values.

For example:

SELECT t1.id, t1.type, t2.name
  FROM table1 t1
  INNER JOIN table2 t2 ON table.xid = table2.id
  WHERE t1.user_id = 100
  AND (t1.type != 'FOO' AND t2.name != 'BAR')

So t1.type is type ENUM with about 10 different options, and t2.name is also type ENUM with 2 options.

My expected results would look a little like:

1, FOO, YUM
2, BOO, BAR
3, BOO, YUM

But instead, all I’m getting is:

3, BOO, YUM

It appears to be filtering out all records which has ‘FOO’ as the type, and ‘BAR’ as the name.

(We’re using MySQL 5.1…)

Answer 1

If I understand your question, you should change your query to use OR:

AND (t1.type != 'FOO' OR t2.name != 'BAR')

This is the same as

AND NOT (t1.type = 'FOO' AND t2.name = 'BAR')

and will remove all rows, where both conditions match.