How do I compare tables of different sizes in sql?

Question

I need to compare a smaller table to a larger table. The smaller table is comprised of 3 fields that recur in the larger table. One of the fields is an id. Another is an area measurement. The last is a string. I need to mark the records in the larger table that have values that disagree with values in the smaller table for a given id. The smaller table has at most 60% of the entries of the larger table. I need to account for duplicates.

I've looked around an I haven't found any real discussion on the topic. I'll be using sqlite3 for this.

Answer 1

A = small table B = large table

select * from B, A
where A.ID = B.MatchingField
AND (A.Measurement <> B.Measurement
OR A.String <> B.String)