查询合并由烦到简三种写法

一、原始 写法

select a.tdtname,b.num,c.num from 
	(select tdtname  from dbo.IKNOW_STATISTICS_U2000V1R7C00  where type='TDT') a
left join 
	(
		select tdtname,count(*) as num from dbo.IKNOW_STORY_U2000V1R7C00 where tdtname  in (
		select tdtName  from dbo.IKNOW_STATISTICS_U2000V1R7C00  where type='TDT')
		group by tdtName
	) b on a.tdtname = b.tdtname
left join 
	(
		select tdtname,count(*) as num from dbo.IKNOW_STORY_U2000V1R7C00 where  tdtname  in (
		select tdtName  from dbo.IKNOW_STATISTICS_U2000V1R7C00  where type='TDT')
		and jirastatename='closed'
		group by tdtName 
	) c on a.tdtname = c.tdtname;

二、效率高一些的写法

select b.tdtname,b.num,c.num from 
	(
		
        select a.tdtname,count(b1.tdtname) as num from 
               IKNOW_STATISTICS_U2000V1R7C00 a
           left join 
               IKNOW_STORY_U2000V1R7C00  b1
           on  a.tdtname = b1.tdtname 
           where a.type='TDT'
           group by a.tdtName 
	) b
left join 
	(
		
        select a.tdtname,count(c1.tdtname) as num from 
               IKNOW_STATISTICS_U2000V1R7C00 a
           left join 
               IKNOW_STORY_U2000V1R7C00  c1
           on  a.tdtname = c1.tdtname  and c1.jirastatename='closed'
           where a.type='TDT'
           group by a.tdtName 
	) c on b.tdtname = c.tdtname;

三、最终写法

select a.tdtname,b.num,c.num from 
	(select tdtname from IKNOW_STATISTICS_U2000V1R7C00 where type='TDT') a
left join 
	(
		select tdtname,count(*) as num from dbo.IKNOW_STORY_U2000V1R7C00 group by tdtName
	) b on a.tdtname = b.tdtname
left join 
	(
		select tdtname,count(*) as num from dbo.IKNOW_STORY_U2000V1R7C00 where  jirastatename='closed'
		group by tdtName 
	) c on a.tdtname = c.tdtname

order by a.tdtname;