Question

这是我的CTE - 它导致错误。帮我弄清楚错误

CREATE TABLE [dbo].[myEmpTab](
[EMPNO] [int] NULL,
[ENAME] [varchar](10)  NULL,
[JOB] [varchar](20)  NULL,
[MGR] [int] NULL,
[HIREDATE] [datetime] NULL,
[SAL] [int] NULL
) ON [PRIMARY]

;
WITH MyCTE AS 
( 
  SELECT EMPNO, EName, Null as MGR, NULL as ManagerName
  FROM myEmpTab
  WHERE MGR IS NULL
  UNION ALL
  SELECT  EMPNO, EName, MGR, MyCTE.EName
  FROM myEmpTab
  INNER JOIN MyCTE ON myEmpTab.MGR = MyCTE.EMPNO
  WHERE myEmpTab.MGR IS NOT NULL 
)
SELECT * FROM MyCTE

当我执行sql时，我收到的错误就像

Msg 209, Level 16, State 1, Line 8
Ambiguous column name 'EMPNO'.
Msg 209, Level 16, State 1, Line 8
Ambiguous column name 'EName'.
Msg 209, Level 16, State 1, Line 8
Ambiguous column name 'MGR'.

我无法发现错误。所以请任何人都有很多，并帮助我解决它。感谢名单。

Answer 1

根据你的编辑，你可能需要像

这样的东西

;WITH MyCTE AS 
( 
  SELECT EMPNO, EName, NULL as MGR, CAST(Null AS  VARCHAR(10)) as ManagerName
  FROM myEmpTab
  WHERE MGR IS NULL
  UNION ALL
  SELECT  myEmpTab.EMPNO, myEmpTab.EName, MyCTE.MGR, MyCTE.EName
  FROM myEmpTab
  INNER JOIN MyCTE ON myEmpTab.MGR = MyCTE.EMPNO
  WHERE myEmpTab.MGR IS NOT NULL 
)
SELECT * FROM MyCTE

Answer 2

我认为你不能在自己内部引用CTE。试试这个

WITH MyCTE AS 
( 
SELECT EMPNO, EName, MGR, Sal
FROM myEmpTab
WHERE MGR IS NULL
)

SELECT EMPNO, EName, MGR, Sal FROM MyCTE

UNION ALL

SELECT  e.EMPNO, e.EName, e.MGR, MyCTE.EName
FROM myEmpTab e
INNER JOIN MyCTE ON e.MGR = MyCTE.EMPNO
WHERE e.MGR IS NOT NULL

OR

WITH MyCTE AS 
( 
    SELECT EMPNO, EName, MGR, Sal
    FROM myEmpTab
    WHERE MGR IS NULL
),
MyCTE2 as
(
    SELECT EMPNO, EName, MGR, Sal FROM MyCTE

    UNION ALL

    SELECT  e.EMPNO, e.EName, e.MGR, MyCTE.EName
    FROM myEmpTab e
    INNER JOIN MyCTE ON e.MGR = MyCTE.EMPNO
    WHERE e.MGR IS NOT NULL 
)
SELECT * FROM MyCTE2

SQL Server CTE给出执行问题

2 个答案: