sql 查詢結果合并union all用法_數據庫技巧

sql語句查詢結果合并union all用法_數據庫技巧,需要的朋友可以參考下。

代碼如下:
–合并重復行
select * from A
union
select * from B

–不合并重復行
select * from A
union all
select * from B

按某個字段排序
–合并重復行
select *
from (
select * from A
union
select * from B) AS T
order by 字段名

–不合并重復行
select *
from (
select * from A
union all
select * from B) AS T
order by 字段名

//sql server版
Select * From (
select top 2 id,adddate,title,url from bArticle where ClassId=1 order by adddate desc) A
Union All
Select * From (
select top 2 id,adddate,title,url from bArticle where ClassId=2 order by adddate desc) B
Union All
Select * From (
select top 2 id,adddate,title,url from bArticle where ClassId=3 order by adddate desc) C
Union All
Select * From (
select top 2 id,adddate,title,url from bArticle where ClassId=4 order by adddate desc) D

//mysql版
Select * From (
select id,adddate,title,url from bArticle where ClassId=1 order by adddate desc limit 0,2) A
Union All
Select * From (
select id,adddate,title,url from bArticle where ClassId=2 order by adddate desc limit 0,2) B
Union All
Select * From (
select id,adddate,title,url from bArticle where ClassId=3 order by adddate desc limit 0,2) C
Union All
Select * From (
select id,adddate,title,url from bArticle where ClassId=4 order by adddate desc limit 0,2) D

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喜歡就支持一下吧
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