text: -- tkt2822.test
  -- 
  -- execsql {
  --     SELECT p PX, q QX FROM t6a UNION ALL SELECT x XX, y YX FROM t6b
  --     ORDER BY t6a.q, XX
  -- }
  SELECT p PX, q QX FROM t6a UNION ALL SELECT x XX, y YX FROM t6b
  ORDER BY t6a.q, XX