--SELECT x.a > (SELECT SUM(y.a) AS b FROM y) FROM x;
--------------------------------------
-- Unnest Subqueries
--------------------------------------
SELECT *
FROM x AS x
WHERE
  x.a = (SELECT SUM(y.a) AS a FROM y)
  AND x.a IN (SELECT y.a AS a FROM y)
  AND x.a IN (SELECT y.b AS b FROM y)
  AND x.a = ANY (SELECT y.a AS a FROM y)
  AND x.a = (SELECT SUM(y.b) AS b FROM y WHERE x.a = y.a)
  AND x.a > (SELECT SUM(y.b) AS b FROM y WHERE x.a = y.a)
  AND x.a <> ANY (SELECT y.a AS a FROM y WHERE y.a = x.a)
  AND x.a NOT IN (SELECT y.a AS a FROM y WHERE y.a = x.a)
  AND x.a IN (SELECT y.a AS a FROM y WHERE y.b = x.a)
  AND x.a < (SELECT SUM(y.a) AS a FROM y WHERE y.a = x.a and y.a = x.b and y.b <> x.d)
  AND EXISTS (SELECT y.a AS a, y.b AS b FROM y WHERE x.a = y.a)
  AND x.a IN (SELECT y.a AS a FROM y LIMIT 10)
  AND x.a IN (SELECT y.a AS a FROM y OFFSET 10)
  AND x.a IN (SELECT y.a AS a, y.b AS b FROM y)
  AND x.a > ANY (SELECT y.a FROM y)
  AND x.a = (SELECT SUM(y.c) AS c FROM y WHERE y.a = x.a LIMIT 10)
  AND x.a = (SELECT SUM(y.c) AS c FROM y WHERE y.a = x.a OFFSET 10)
  AND x.a > ALL (SELECT y.c FROM y WHERE y.a = x.a)
  AND x.a > (SELECT COUNT(*) as d FROM y WHERE y.a = x.a)
  AND x.a = SUM(SELECT 1)  -- invalid statement left alone
;
SELECT
  *
FROM x AS x
CROSS JOIN (
  SELECT
    SUM(y.a) AS a
  FROM y
) AS _u_0
LEFT JOIN (
  SELECT
    y.a AS a
  FROM y
  GROUP BY
    y.a
) AS _u_1
  ON x.a = _u_1.a
LEFT JOIN (
  SELECT
    y.b AS b
  FROM y
  GROUP BY
    y.b
) AS _u_2
  ON x.a = _u_2.b
LEFT JOIN (
  SELECT
    y.a AS a
  FROM y
  GROUP BY
    y.a
) AS _u_3
  ON x.a = _u_3.a
LEFT JOIN (
  SELECT
    SUM(y.b) AS b,
    y.a AS _u_5
  FROM y
  WHERE
    TRUE
  GROUP BY
    y.a
) AS _u_4
  ON x.a = _u_4._u_5
LEFT JOIN (
  SELECT
    SUM(y.b) AS b,
    y.a AS _u_7
  FROM y
  WHERE
    TRUE
  GROUP BY
    y.a
) AS _u_6
  ON x.a = _u_6._u_7
LEFT JOIN (
  SELECT
    y.a AS a
  FROM y
  WHERE
    TRUE
  GROUP BY
    y.a
) AS _u_8
  ON _u_8.a = x.a
LEFT JOIN (
  SELECT
    y.a AS a
  FROM y
  WHERE
    TRUE
  GROUP BY
    y.a
) AS _u_9
  ON _u_9.a = x.a
LEFT JOIN (
  SELECT
    ARRAY_AGG(y.a) AS a,
    y.b AS _u_11
  FROM y
  WHERE
    TRUE
  GROUP BY
    y.b
) AS _u_10
  ON _u_10._u_11 = x.a
LEFT JOIN (
  SELECT
    SUM(y.a) AS a,
    y.a AS _u_13,
    ARRAY_AGG(y.b) AS _u_14
  FROM y
  WHERE
    TRUE AND TRUE AND TRUE
  GROUP BY
    y.a
) AS _u_12
  ON _u_12._u_13 = x.a AND _u_12._u_13 = x.b
LEFT JOIN (
  SELECT
    y.a AS a
  FROM y
  WHERE
    TRUE
  GROUP BY
    y.a
) AS _u_15
  ON x.a = _u_15.a
LEFT JOIN (
  SELECT
    ARRAY_AGG(c),
    y.a AS _u_20
  FROM y
  WHERE
    TRUE
  GROUP BY
    y.a
) AS _u_19
  ON _u_19._u_20 = x.a
LEFT JOIN (
  SELECT
    COUNT(*) AS d,
    y.a AS _u_22
  FROM y
  WHERE
    TRUE
  GROUP BY
    y.a
) AS _u_21
  ON _u_21._u_22 = x.a
WHERE
  x.a = _u_0.a
  AND NOT _u_1.a IS NULL
  AND NOT _u_2.b IS NULL
  AND NOT _u_3.a IS NULL
  AND x.a = _u_4.b
  AND x.a > _u_6.b
  AND x.a = _u_8.a
  AND NOT x.a = _u_9.a
  AND ARRAY_ANY(_u_10.a, _x -> _x = x.a)
  AND (
    x.a < _u_12.a AND ARRAY_ANY(_u_12._u_14, "_x" -> _x <> x.d)
  )
  AND NOT _u_15.a IS NULL
  AND x.a IN (
    SELECT
      y.a AS a
    FROM y
    LIMIT 10
  )
  AND x.a IN (
    SELECT
      y.a AS a
    FROM y
    OFFSET 10
  )
  AND x.a IN (
    SELECT
      y.a AS a,
      y.b AS b
    FROM y
  )
  AND x.a > ANY (
    SELECT
      y.a
    FROM y
  )
  AND x.a = (
    SELECT
      SUM(y.c) AS c
    FROM y
    WHERE
      y.a = x.a
    LIMIT 10
  )
  AND x.a = (
    SELECT
      SUM(y.c) AS c
    FROM y
    WHERE
      y.a = x.a
    OFFSET 10
  )
  AND ARRAY_ALL(_u_19."", _x -> _x = x.a)
  AND x.a > COALESCE(_u_21.d, 0)
  AND x.a = SUM(SELECT
    1) /* invalid statement left alone */
;
SELECT
  CAST((
    SELECT
      x.a AS a
    FROM x
  ) AS TEXT) AS a;
SELECT
  CAST((
    SELECT
      x.a AS a
    FROM x
  ) AS TEXT) AS a;