Sql server 如何在同一select语句中使用条件列值?
我有点像 (Sql server 如何在同一select语句中使用条件列值?,sql-server,sql-server-2008,case,conditional-statements,Sql Server,Sql Server 2008,Case,Conditional Statements,我有点像 (COMPLEX\u EXPRESSION\u N表示长子查询) 是否可以像我在AllChecksOk行中那样使用FirstCheck、SecondCheck、ThirdCheck 我不关心性能,这是一种每天手动运行一次的操作,只需要很少的记录,我只是想避免创建视图、表或临时表,并将所有内容保存在一个select语句中 作为替代,我可以这样做,但这会降低查询的可读性(因为我需要为每个复杂表达式编写两次): 您不能在选择中引用列别名,但可以使用如下CTE ;WITH CTE AS ( s
COMPLEX\u EXPRESSION\u N
表示长子查询)
是否可以像我在AllChecksOk行中那样使用FirstCheck、SecondCheck、ThirdCheck
我不关心性能,这是一种每天手动运行一次的操作,只需要很少的记录,我只是想避免创建视图、表或临时表,并将所有内容保存在一个select语句中
作为替代,我可以这样做,但这会降低查询的可读性(因为我需要为每个复杂表达式编写两次):
您不能在
选择中引用列别名,但可以使用如下CTE
;WITH CTE AS
(
select
ID_Operation,
FirstCheck = CASE WHEN (COMPLEX_EXPRESSION_1)= 0 then 0 else 1 end,
SecondCheck = CASE WHEN (COMPLEX_EXPRESSION_2)= 0 then 0 else 1 end,
ThirdCheck = CASE WHEN (COMPLEX_EXPRESSION_3)= 0 then 0 else 1 end
from
AllOperationsTable
)
SELECT *,
AllChecksOk = Case WHEN
(COMPLEX_EXPRESSION_1+ COMPLEX_EXPRESSION_2+
COMPLEX_EXPRESSION_3CHeck = 3) Then 'OK' Else 'No' End
FROM CTE
您还可以使用交叉应用
定义3列别名,然后在主选择
列表中引用它们。下面是一个派生表解决方案
SELECT
T.ID_Operation,
FirstCheck = CASE WHEN T.Expr1 = 0 THEN 0 ELSE 1 END,
SecondCheck = CASE WHEN T.Expr2 = 0 THEN 0 ELSE 1 END,
ThirdCheck = CASE WHEN T.Expr3 = 0 THEN 0 ELSE 1 END,
AllChecksOk = CASE WHEN T.Expr1 + T.Expr2 + T.Expr3 = 3 THEN 'OK' ELSE 'No' END
FROM
(
SELECT
ID_Operation,
Expr1 = (COMPLEX_EXPRESSION_1),
Expr2 = (COMPLEX_EXPRESSION_2),
Expr3 = (COMPLEX_EXPRESSION_3)
FROM
AllOperationsTable
) T
CTE做了这项工作,我不想交叉申请,我会把它记下来以备将来使用。谢谢
;WITH CTE AS
(
select
ID_Operation,
FirstCheck = CASE WHEN (COMPLEX_EXPRESSION_1)= 0 then 0 else 1 end,
SecondCheck = CASE WHEN (COMPLEX_EXPRESSION_2)= 0 then 0 else 1 end,
ThirdCheck = CASE WHEN (COMPLEX_EXPRESSION_3)= 0 then 0 else 1 end
from
AllOperationsTable
)
SELECT *,
AllChecksOk = Case WHEN
(COMPLEX_EXPRESSION_1+ COMPLEX_EXPRESSION_2+
COMPLEX_EXPRESSION_3CHeck = 3) Then 'OK' Else 'No' End
FROM CTE
SELECT
T.ID_Operation,
FirstCheck = CASE WHEN T.Expr1 = 0 THEN 0 ELSE 1 END,
SecondCheck = CASE WHEN T.Expr2 = 0 THEN 0 ELSE 1 END,
ThirdCheck = CASE WHEN T.Expr3 = 0 THEN 0 ELSE 1 END,
AllChecksOk = CASE WHEN T.Expr1 + T.Expr2 + T.Expr3 = 3 THEN 'OK' ELSE 'No' END
FROM
(
SELECT
ID_Operation,
Expr1 = (COMPLEX_EXPRESSION_1),
Expr2 = (COMPLEX_EXPRESSION_2),
Expr3 = (COMPLEX_EXPRESSION_3)
FROM
AllOperationsTable
) T