SELECT COUNT(*)
INTO v_ctr
FROM leave_type_govt_service
WHERE (
      :block_name.min BETWEEN minimum AND maximum
OR    :block_name.max BETWEEN minimum AND maximum
      )
AND type = :block_name.type;
IF v_ctr > 0 THEN
MESSAGE('Minimum and Maximum Overlaps!');
MESSAGE('Minimum and Maximum Overlaps!');
END IF;

Minimum Maximum
1         5 
6         10
11        15

	AND ROWID <> :leave_type_govt_service.rowid;