Question

I am having trouble with the relational algebra and transformation into SQL of this rather complicated query:

I need to select all values from table A joined to table B where there are no matching records in table B, or there are matching records but the set of matching records do not have a field that contains one of 4 of a possible 8 total values.

Database is MySQL 5.0… using an InnoDB engine for the tables.

Answer 1

I’m not sure if there is any real performance improvement but one other way is:

SELECT 
    *
FROM
    tableA
WHERE
    id NOT IN ( SELECT id FROM tableB WHERE field1 NOT IN ("value1", "value2"));