Question

I have a table ABR with three columns: two lookup values, A and B and a result Result. I want the result to be returned given A and B

But, for some values of A, column B can be a wildcard. In that case I want the most specific row.

I can’t seem to figure out the MySQL statement though – I found one, but it was 7 lines long and had 5 = and two IF‘s, there must be a better way.

A   B   Result
1   *   First
2   *   Second
2   1   Third
2   2   Fourth
3   *   Fifth

Example wanted results:
A=1, B=5 -> First
A=1, B=0 -> First
A=2, B=2 -> Fourth
A=2, B=4 -> Second
A=3, B=7 -> Fifth

Do notice that the column values can change later: we can add extra rows for A and B, or remove values. Hardcoding stuff in the SQL is not acceptable.

Answer 1

SELECT Result
    FROM ABR
    WHERE A = @LookupA
        AND (B = @LookupB OR B = '*')
    ORDER BY B DESC LIMIT 1;