• If a list of fields is to be returned, specify them prefixed by their table's alias name as specified in the From Clause.

• Use the DISTINCT option when the result list of records may contain duplicate rows in respect to the specified list of fields AND only one copy of the duplicated rows is needed.

• For top-level batch programs, always specify the WITH HOLD keyword on the main SQL of a cursor based processing. This is to keep the cursor open after a commit or rollback. Without this, main cursor will be closed and fetch of the next record or restart processing will fail (specific to DB2) with SQL error 501.