MSSQL 臨時表和公用表使用案例
阿新 • • 發佈:2017-05-19
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1、臨時表:
1.1)實例1
if(OBJECT_ID(‘tempdb..#a‘) IS NOT NULL) drop table #a;
if(OBJECT_ID(‘tempdb..#b‘) IS NOT NULL) drop table #b;
SELECT name into #a from syscolumns a with(nolock) where id=OBJECT_ID(‘NewsLetterSystem_Subscriber‘);
SELECT name into #b from syscolumns b where id=OBJECT_ID(‘tmpContact_130828005535769_5243_f0b7 ‘);
select * from #a,#b
where #a.name=#b.name;
1.2) 實例2
if(OBJECT_ID(‘tempdb..#a‘) IS NOT NULL) drop table #a;
select * into #a from Categories;
select * from #a;
2、公用表:
2.1)實例1
with
cr as
(
select CountryRegionCode from person.CountryRegion where Name like ‘C%‘
)
select * from person.StateProvince where CountryRegionCode in (select * from cr)
--其中cr是一個公用表表達式,該表達式在使用上與表變量類似
2.2) CTE後面必須直接跟使用CTE的SQL語句(如select、insert、update等),否則,CTE將失效。如下面的SQL語句將無法正常使用CTE:
with
cr as
(
select CountryRegionCode from person.CountryRegion where Name like ‘C%‘
)
select * from person.CountryRegion -- 應將這條SQL語句去掉
-- 使用CTE的SQL語句應緊跟在相關的CTE後面 --
select * from person.StateProvince where CountryRegionCode in (select * from cr)
2.3)CTE後面也可以跟其他的CTE,但只能使用一個with,多個CTE中間用逗號(,)分隔,如下面的SQL語句所示:
with
cte1 as
(
select * from table1 where name like ‘abc%‘
),
cte2 as
(
select * from table2 where id > 20
),
cte3 as
(
select * from table3 where price < 100
)
select a.* from cte1 a, cte2 b, cte3 c where a.id = b.id and a.id = c.id
2.4)實例4
with ta as (
SELECT name from syscolumns a with(nolock) where id=OBJECT_ID(‘NewsLetterSystem_Subscriber‘)
),
tb as
(
SELECT name from syscolumns b where id=OBJECT_ID(‘tmpContact_130828005535769_5243_f0b7‘)
)
select * from ta,tb where ta.name=tb.name
MSSQL 臨時表和公用表使用案例