我用过一次后为什么不能访问我的CTE？

Question

我的存储过程如下:

WITH MYCTE(....)
AS 
(
...
)

UPDATE ... (using my CTE)



DELETE ( using my CTE)  <---  says the object, my CTE, doesn't exist

我可以只使用一次吗？

Answer 1

在您的示例代码中,CTE仅持续UPDATE.如果你需要它持续更长时间,可以考虑用它填充#tempTable或@tableVariable,然后从那些中填充UPDATE和DELETE.

您还可以扩充UPDATE以使用OUTPUT子句,如下所示,以便捕获受影响的行.并在DELETE中使用它们,如下所示:

set nocount on
DECLARE @Table     table (PK int, col1 varchar(5))
DECLARE @SavedPks  table (PK int)

INSERT INTO @Table VALUES (1,'g')
INSERT INTO @Table VALUES (2,'g')
INSERT INTO @Table VALUES (3,'g')
INSERT INTO @Table VALUES (4,'g')
INSERT INTO @Table VALUES (5,'x')
INSERT INTO @Table VALUES (6,'x')
set nocount off

;WITH MYCTE
AS 
(
  SELECT PK, col1 FROM @Table
)
UPDATE MYCTE
    SET col1='xyz'
    OUTPUT INSERTED.PK
        INTO @SavedPks
    WHERE col1='g'

SELECT 'A',* FROM @Table

DELETE @Table
    WHERE PK IN (SELECT PK  from @SavedPks)

SELECT 'B',* FROM @Table

OUTPUT:

(4 row(s) affected)
     PK          col1
---- ----------- -----
A    1           xyz
A    2           xyz
A    3           xyz
A    4           xyz
A    5           x
A    6           x

(6 row(s) affected)

(4 row(s) affected)

     PK          col1
---- ----------- -----
B    5           x
B    6           x

(2 row(s) affected)