In the next query, the SELECT order is reversed:
SELECT level, param 'GMKSA CONTROL' (TITLE 'OWNER') FROM gmksa_control WHERE cycle = '03' UNION SELECT level, param, 'GMKSA' FROM gmksa WHERE cycle = '03' ORDER BY 1, 2;
This query returns the following answer set:
***QUERY COMPLETED.10 ROWS FOUND. 3 COLUMNS RETURNED. LEVEL PARAM OWNER ----- ----- ------------- 00 A GMKSA 00 A GMKSA CONTROL 00 T GMKSA 00 T GMKSA CONTROL 85 X GMKSA 85 X GMKSA CONTROL SF A GMKSA SF A GMKSA CONTROL SF T GMKSA SF T GMKSA CONTROL
In this case, because the first SELECT specified ‘GMKSA CONTROL’, the rows were not duplicates and were included in the answer set.