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[英]update with join on CTE doesn't use index, but with temp table it does
[英]How to join multiple CTE's into a temp table
已为我提供了清理脚本的脚本,该脚本使用了大约85个临时表,建议我使用通用表表达式。
我有3个CTE,第一个是使用Union all将7个表组合在一起的结果。 其次是2个CTE。 该脚本运行到:
select * from CTE_1
Union all
select * from CTE_2
Union all
select * from CTE_3
然后,我想将所有这些结果放入可重用的表中,以便随后可以使用各种case语句逻辑添加一些联接。 如何将它们放入临时表中,以便以后使用。
我希望减少临时表的数量,而不是将每个CTE放入一个临时表中,而我最好将多个CTE放入一个临时表中。 我目前有:
; with [CTE One] as (
select 1 as col
),
[CTE Two] as (
select 2 as col
),
[CTE Three] as (
select 3 as col
)
select * from CTE_1
Union all
select * from CTE_2
Union all
select * from CTE_3
您不能只使用into
吗?
select *
into #temptable
from CTE_1
Union all
select * from CTE_2
Union all
select * from CTE_3;
如果代码结构适当,我可能还会倾向于使用表变量。
或者..
IF ( OBJECT_ID('tempdb..#temptable') IS NOT NULL )
BEGIN
DROP TABLE #temptable
END
CREATE TABLE #temptable
(
val int
)
;
WITH [CTE One]
AS ( SELECT 1 AS col
),
[CTE Two]
AS ( SELECT 2 AS col
),
[CTE Three]
AS ( SELECT 3 AS col
)
INSERT INTO #temptable (val)
SELECT *
FROM ( SELECT *
FROM CTE_1
UNION ALL
SELECT *
FROM CTE_2
UNION ALL
SELECT *
FROM CTE_3
) T
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