昨天晚上,我正在写一个这样的简单的T-sql程序
DECLARE @ROLEID AS INT
SELECT @ROLEID = [ROLE ID] FROM TBLROLE
;WITH CTE
AS
(
SELECT * FROM SOMetaBLE
)
IF (@ROLEID = 1)
BEGIN
//SOMECODE
END
ELSE IF(@ROLEID = 2)
BEGIN
//SOMECODE
END
ELSE
BEGIN
//SOMECODE
END
哪里不对？
但是,我用另外一种方式做到了.但是我想知道为什么它不起作用！
解决方法
Common table expressions在单个语句的上下文中定义：
WITH cte_name AS ( <cte definition>) <statement that uses cte>;
所以你可以做一些事情：
WITH CTE
AS
(
SELECT * FROM SOMetaBLE
)
SELECT * FROM CTE;
要么
WITH CTE
AS
(
SELECT * FROM SOMetaBLE
)
UPDATE CTE
SET somefield = somevalue
WHERE id = somekey;
A CTE must be followed by a single SELECT,INSERT,UPDATE,MERGE,or DELETE statement that references some or all the CTE columns. A CTE can also be specified in a CREATE VIEW statement as part of the defining SELECT statement of the view
