select varid,sellprice from realdata where rdid in( select max(rdid) from realdata group by (varid))
语句是这样的,用的是_RecordsetPtr , 语句直接在sql中执行没错, 用ado连接后查询不到结果。
是不是 ADO 对group by 支持有问题?
语句是这样的,用的是_RecordsetPtr , 语句直接在sql中执行没错, 用ado连接后查询不到结果。
是不是 ADO 对group by 支持有问题?
这样执行就没问题?
WHERE NOT EXISTS(SELECT 1 FROM realdata WHERE varid=R.varid AND RDID>T.RDID)
where rdid in
( select max(rdid) from realdata WHERE RDID IS NOT NULL
group by varid) 去掉GROUP BY 括号试试,
Ado肯定会支持group by的
where rdid a exists( select max(rdid) from realdata where rdid=a.rdid group by (varid))
这样试试
如果没有结果,将上面语句分开执行看看
where exists( select max(rdid) from realdata where rdid=a.rdid group by (varid))
select
varid,sellprice
from
realdata
where
rdid in( select max(rdid) as rdid,varid from realdata group by (varid))
select varid,sellprice from realdata
where rdid in
( select rdid from realdata t
where not exists( select 1 from realdata WHERE varid=t.varid an rdid>t.rdid)
)
---try
select
varid,sellprice
from
realdata
where
rdid
in
( select raid from (select max(rdid) as rdid,varid from realdata group by (varid))t)
INNER JOIN (
select varid, max(rdid),'RDID' from realdata group by varid
) T ON realdata.VARID=T.VARID AND realdata.RDID=T.RDID
WHERE NOT EXISTS(SELECT 1 FROM realdata WHERE varid=R.varid AND RDID>R.RDID)这样试试,
go
create table realdata(id int identity(1,1),姓名 varchar(10) , 课程 varchar(10) , 分数 int)
insert into realdata(姓名,课程,分数) values('张三' , '语文' , 74)
insert into realdata(姓名,课程,分数) values('张三' , '数学' , 83)
insert into realdata(姓名,课程,分数) values('张三' , '物理' , 93)
insert into realdata(姓名,课程,分数) values('李四' , '语文' , 74)
insert into realdata(姓名,课程,分数) values('李四' , '数学' , 84)
insert into realdata(姓名,课程,分数) values('李四' , '物理' , 94)
select id,姓名,课程,分数 from realdata a
where not exists( select 1 from realdata where 姓名=a.姓名 and 分数>a.分数)
--相同记录取最大!
select id,姓名,课程,分数 from realdata a
where not exists( select 1 from realdata where 姓名=a.姓名 and 分数<a.分数)
--相同姓名取最小
/******************************************************************************************************************************************************
1、Num、Name相同的重复值记录,没有大小关系只保留一条
2、Name相同,ID有大小关系时,保留大或小其中一个记录
整理人:中国风(Roy)日期:2008.06.06
******************************************************************************************************************************************************/--1、用于查询重复处理记录(如果列没有大小关系时2000用生成自增列和临时表处理,SQL2005用row_number函数处理)--> --> (Roy)生成測試數據
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)
*/
group by 后面的字段加上括号可以查询出结果的
数据库都支持 group by