Question

这是（非常）更大查询的一部分。

错误是缺少的别名＆＃34; clienti_con_rinnovo＆＃34; （表＆＃34; clienti_con_rinnovo＆＃34;不存在）。我不需要重写查询（逻辑是正确的）但可能有助于获得别名。

如果感兴趣（但您知道），订单为LEFT JOIN，并且跟随UNION。

提前谢谢

SELECT * FROM
( SELECT
    id,
    MAX(dateTransaction) AS last_transaction_renew
    FROM transactions
    WHERE
    renew IS NOT NULL
    GROUP BY id ) AS clienti_con_rinnovo

UNION                                           

SELECT * FROM

    ( SELECT
            id,
            MAX(dateTransaction) AS last_transaction_renew
      FROM transactions
      WHERE renew IS NULL
      GROUP BY id ) AS clienti_senza_rinnovo

      LEFT JOIN clienti_con_rinnovo ON clienti_con_rinnovo.id = clienti_senza_rinnovo.id
      WHERE clienti_con_rinnovo.id IS NULL

Answer 1

一种可能的解决方案是创建一个视图，因此每次执行该查询时都不需要将大量数据加载到结果中。也更容易维护，因为您可以在视图内部进行过滤或删除不再需要的列。

示例：

CREATE VIEW clienti_con_rinnovo
AS
SELECT
    id,
    MAX(dateTransaction) AS last_transaction_renew
    FROM transactions
    WHERE
    renew IS NOT NULL
    GROUP BY id

但你的尝试几乎正常。尝试：

SELECT clienti_con_rinnovo.* FROM
( SELECT
    id,
    MAX(dateTransaction) AS last_transaction_renew
    FROM transactions
    WHERE
    renew IS NOT NULL
    GROUP BY id ) AS clienti_con_rinnovo

和你的另一张桌子相同：

SELECT clienti_senza_rinnovo.* FROM
    ( SELECT
            id,
            MAX(dateTransaction) AS last_transaction_renew
      FROM transactions
      WHERE renew IS NULL
      GROUP BY id ) AS clienti_senza_rinnovo

Answer 2

我不确定你要做什么，但别名不会像你在这里尝试实现的那样工作。尝试使用此

SELECT * FROM
 ( SELECT
 id,
 MAX(dateTransaction) AS last_transaction_renew
 FROM transactions
 WHERE
 renew IS NOT NULL
 GROUP BY id ) AS clienti_con_rinnovo_new

 UNION

 SELECT clienti_senza_rinnovo.* FROM 
 ( SELECT
   id,
   MAX(dateTransaction) AS last_transaction_renew
     FROM transactions
    WHERE
    renew IS NOT NULL
  GROUP BY id ) AS clienti_con_rinnov
LEFT JOIN 
(SELECT
   id,
  MAX(dateTransaction) AS last_transaction_renew
  FROM transactions
  WHERE renew IS NULL
  GROUP BY id ) AS clienti_senza_rinnovo ON clienti_con_rinnovo.id = 
  clienti_senza_rinnovo.id 
  WHERE clienti_con_rinnovo.id IS NULL

MySQL：别名表不存在（复杂的子查询）

2 个答案: