嵌套 MySQL 查询列别名

Question

这是一个有效的 MySQL 查询，您可以使用嵌套查询之外的列的别名吗？（series_id_a和series_id_b是函数输入，这个应该用在函数中）

select x1 as x1a, x2 as x2a, y1 as y1a, y2 as y2a FROM region WHERE series_id = series_id_a AND EXISTS(
                    SELECT x1 as x1b, x2 as x2b, y1 as y1b, y2 as y2b FROM region WHERE series_id = series_id_b AND x1b = x1a AND x2b = x2a AND y1a = y1b AND y2a = y2b
                )

Answer 1

不，在 WHERE 子句的条件中引用分配给外部查询中的表达式的列别名是无效的。

为了清楚起见，为了未来读者的理智，为了这个世界上所有美好的事物...限定所有专栏引用。

作为我猜测您正在尝试实现的目标的示例：

 SELECT r.x1 AS x1a
      , r.x2 AS x2a
      , r.y1 AS y1a
      , r.y2 AS y2a 
   FROM region r
  WHERE r.series_id =  ?  -- series_id_a parameter
    AND EXISTS ( SELECT 1
                   FROM region q
                  WHERE q.series_id =  ? -- series_id_b parameter
                    AND q.x1 = r.x1
                    AND q.x2 = r.x2
                    AND q.y1 = r.y1
                    AND q.y2 = r.y2
                )

嵌套 MySQL 查询列别名

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