SQL Server - Select first row that meets criteria

Question

I have 2 tables that contain IDs. There will be duplicate IDs in one of the tables and I only want to return one row for each matching ID in table B. For example:

Table

Answer 1

You should use PARTITION OVER to achieve the results.

   SELECT 
        t.objectIdA,
        t.objectIdB
    FROM (
      SELECT
         a.objectIdA,
         a.objectIdB,
        rowid = ROW_NUMBER() OVER (PARTITION BY a.objectIdA ORDER BY a.objectIdB DESC)
      FROM TableA a
       INNER JOIN TableB b ON (a.objectIdA = b.objectIdA)
    ) t
    WHERE rowid <= 1

Fiddle Code: http://sqlfiddle.com/#!3/a2ccd/1