MySQL 子查询的别名不起作用

Question

我将此代码写入我的 MySQL 终端，但 MySQL 响应 "ERROR 1054 (42S22): Unknown column 'a.SD_ID' in 'on clause'"

我不知道为什么它不理解我的别名。

SELECT  t.TBL_NAME              AS 'TABLE',
t.TBL_TYPE                      AS 'TYPE',
a.COLUMN_NAME                   AS 'COLUMN_NAME',
a.TYPE_NAME                     AS 'TYPE'
   FROM TBLS t
   JOIN
       (SELECT c.TYPE_NAME, c.COLUMN_NAME, c.CD_ID
           FROM COLUMNS_V2 c, SDS s
           WHERE c.CD_ID = s.CD_ID) a
   ON t.SD_ID = a.SD_ID
WHERE t.TBL_TYPE = 'MANAGED_TABLE'
ORDER BY b.TBL_NAME, b.INTEGER_IDX;

我在 Ubuntu 系统的 MySQL 上查询了这个。

Answer 1

您需要在 subquery 中包含 SD_ID 列。检查下面的注释行。也更喜欢 ANSI 样式的连接：

SELECT  
 t.TBL_NAME    AS 'TABLE',
 t.TBL_TYPE    AS 'TYPE',
 a.COLUMN_NAME AS 'COLUMN_NAME',
 a.TYPE_NAME   AS 'TYPE'
FROM TBLS t
  INNER JOIN
     (SELECT c.TYPE_NAME, c.COLUMN_NAME, c.CD_ID -- include either c.SD_ID or s.SD_ID
      FROM COLUMNS_V2 c 
      inner join SDS s
      on c.CD_ID = s.CD_ID
     ) a
   ON t.SD_ID = a.SD_ID
WHERE t.TBL_TYPE = 'MANAGED_TABLE'
ORDER BY b.TBL_NAME, b.INTEGER_IDX;

MySQL 子查询的别名不起作用

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