sql查询结果合并unionall用法_数据库技巧

来源：懂视网责编：小采时间：2020-11-09 07:14:06

sql查询结果合并unionall用法_数据库技巧

sql查询结果合并unionall用法_数据库技巧: 代码如下:--合并重复行 select * from A union select * from B --不合并重复行 select * from A union all select * from B 按某个字段排序 --合并重复行 select * from ( select * from A union select *

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导读sql查询结果合并unionall用法_数据库技巧: 代码如下:--合并重复行 select * from A union select * from B --不合并重复行 select * from A union all select * from B 按某个字段排序 --合并重复行 select * from ( select * from A union select *

代码如下:
--合并重复行
select * from A
union
select * from B

--不合并重复行
select * from A
union all
select * from B

按某个字段排序
--合并重复行
select *
from (
select * from A
union
select * from B) AS T
order by 字段名

--不合并重复行
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