sql - why can't I access my CTE after I used it once?

Question

My stored procedure looks like:

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

UPDATE ... (using my CTE)



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

Can I only use it once?

Answer 1

In your example code, the CTE only persists for the UPDATE. If you need it to last longer, consider populating a #tempTable or @tableVariable with it, and then UPDATE and DELETE from those.

You may also augment your UPDATE to use an OUTPUT clause, like the following, so you can capture the affected rows. And use them in the DELETE, like here:

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)