34,838
社区成员




select * from tb where not exists(select 1 from tb a where a.col=b.col)
一般这种写法,你10W数据应该不会很慢,你直接把需要的列写出来,不用 '*' 这个代替,然后看看你执行计划。包括I/O性能。
if not object_id('Tempdb..#T') is null
drop table #T
Go
Create table #T([ID] int,[STEPID] nvarchar(64),[PROCESSNAME] nvarchar(256),[STEPLABEL] nvarchar(256),[INCIDENT] nvarchar(64))
Insert #T
select 1,N'011656',N'流程1',N'步骤A',N'实例1' union all
select 2,N'011656',N'流程1',N'步骤A',N'实例2' union all
select 3,N'011656',N'流程1',N'步骤A',N'实例3' union all
select 4,N'011656',N'流程1',N'步骤A',N'实例4' union all
select 5,N'011657',N'流程2',N'步骤B',N'实例1' union all
select 6,N'011657',N'流程2',N'步骤B',N'实例2' union all
select 7,N'011657',N'流程2',N'步骤B',N'实例3' union all
select 8,N'011657',N'流程2',N'步骤B',N'实例4' union all
select 9,N'011657',N'流程2',N'步骤B',N'实例5'
Go
select * from Ultiums As a
Where Not exists(select 1 from Ultiums As x
Where x.STEPID=a.STEPID And x.STARTTIME>a.STARTTIME
)
/****** 对象: Index [INCCON3] 脚本日期: 12/14/2012 09:52:27 ******/
ALTER TABLE [dbo].[TASKS] ADD CONSTRAINT [INCCON3] PRIMARY KEY CLUSTERED
(
[TASKID] ASC
)WITH (SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF) ON [PRIMARY]
/****** 对象: Index [TASKS01] 脚本日期: 12/14/2012 09:52:48 ******/
CREATE NONCLUSTERED INDEX [TASKS01] ON [dbo].[TASKS]
(
[PROCESSNAME] ASC,
[PROCESSVERSION] ASC,
[INCIDENT] ASC,
[STEPID] ASC,
[TASKID] ASC
)WITH (SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF) ON [PRIMARY]
/****** 对象: Index [TASKS02] 脚本日期: 12/14/2012 09:53:05 ******/
CREATE NONCLUSTERED INDEX [TASKS02] ON [dbo].[TASKS]
(
[PROCESSNAME] ASC,
[INCIDENT] ASC,
[STEPID] ASC
)WITH (SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF) ON [PRIMARY]
CREATE NONCLUSTERED INDEX [TASKS03] ON [dbo].[TASKS]
(
[STATUS] ASC,
[SUBSTATUS] ASC,
[REFERER] ASC
)WITH (SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF) ON [PRIMARY]
CREATE NONCLUSTERED INDEX [TASKS04] ON [dbo].[TASKS]
(
[RECIPIENTTYPE] ASC,
[STATUS] ASC,
[SUBSTATUS] ASC,
[OVERDUETIME] ASC
)WITH (SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF) ON [PRIMARY]
CREATE NONCLUSTERED INDEX [TASKS05] ON [dbo].[TASKS]
(
[INCIDENT] ASC
)WITH (SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF) ON [PRIMARY]
if not object_id('Tempdb..#T') is null
drop table #T
Go
Create table #T([ID] int,[Name] nvarchar(1),[Memo] nvarchar(2))
Insert #T
select 1,N'A',N'A1' union all
select 2,N'A',N'A2' union all
select 3,N'A',N'A3' union all
select 4,N'B',N'B1' union all
select 5,N'B',N'B2'
Go
--I、Name相同ID最小的记录(推荐用1,2,3),方法3在SQl05时,效率高于1、2
方法1:
Select * from #T a where not exists(select 1 from #T where Name=a.Name and ID<a.ID)
方法2:
select a.* from #T a join (select min(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID
方法3:
select * from #T a where ID=(select min(ID) from #T where Name=a.Name)
方法4:
select a.* from #T a join #T b on a.Name=b.Name and a.ID>=b.ID group by a.ID,a.Name,a.Memo having count(1)=1
方法5:
select * from #T a group by ID,Name,Memo having ID=(select min(ID)from #T where Name=a.Name)
方法6:
select * from #T a where (select count(1) from #T where Name=a.Name and ID<a.ID)=0
方法7:
select * from #T a where ID=(select top 1 ID from #T where Name=a.name order by ID)
方法8:
select * from #T a where ID!>all(select ID from #T where Name=a.Name)
方法9(注:ID为唯一时可用):
select * from #T a where ID in(select min(ID) from #T group by Name)
--SQL2005:
方法10:
select ID,Name,Memo from (select *,min(ID)over(partition by Name) as MinID from #T a)T where ID=MinID
方法11:
select ID,Name,Memo from (select *,row_number()over(partition by Name order by ID) as MinID from #T a)T where MinID=1
生成结果:
/*
ID Name Memo
----------- ---- ----
1 A A1
4 B B1
(2 行受影响)
*/
--II、Name相同ID最大的记录,与min相反:
方法1:
Select * from #T a where not exists(select 1 from #T where Name=a.Name and ID>a.ID)
方法2:
select a.* from #T a join (select max(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID order by ID
方法3:
select * from #T a where ID=(select max(ID) from #T where Name=a.Name) order by ID
方法4:
select a.* from #T a join #T b on a.Name=b.Name and a.ID<=b.ID group by a.ID,a.Name,a.Memo having count(1)=1
方法5:
select * from #T a group by ID,Name,Memo having ID=(select max(ID)from #T where Name=a.Name)
方法6:
select * from #T a where (select count(1) from #T where Name=a.Name and ID>a.ID)=0
方法7:
select * from #T a where ID=(select top 1 ID from #T where Name=a.name order by ID desc)
方法8:
select * from #T a where ID!<all(select ID from #T where Name=a.Name)
方法9(注:ID为唯一时可用):
select * from #T a where ID in(select max(ID) from #T group by Name)
--SQL2005:
方法10:
select ID,Name,Memo from (select *,max(ID)over(partition by Name) as MinID from #T a)T where ID=MinID
方法11:
select ID,Name,Memo from (select *,row_number()over(partition by Name order by ID desc) as MinID from #T a)T where MinID=1
生成结果2:
/*
ID Name Memo
----------- ---- ----
3 A A3
5 B B2
(2 行受影响)
*/
如果还不能解决问题 建议楼主给出具体需求 是根据哪个字段来去重复的
select * from tb where not exists(select 1 from tb a where a.col=b.col)