text: -- tkt2927.test
  -- 
  -- db eval {
  --     SELECT a+b, a-b, abs(a), abs(b) FROM t1
  --     UNION ALL
  --     SELECT a+b, a-b, a, b FROM t1
  -- }
  SELECT a+b, a-b, abs(a), abs(b) FROM t1
  UNION ALL
  SELECT a+b, a-b, a, b FROM t1