简单sql忘高手解答!明天下班结帖!
- SQL code
select hotelname,roomType, hotelid,hoteladdress, sum(isnull(ordercost,0)) as ordertotal from HotelOroder order by hotelid desc group by hotelname,roomType, hotelid,hoteladdress
上面个SQL我想根据rooomType房间类型分组 查询信息,但查询出来的有好多房间类型一样 怎么除去房间类型重复列 并根据房间类型分组?
还有一个问题 如果两表联合查询 怎么除去重复列 有好的文章可以参考吗 谢谢!
[解决办法]
- SQL code
--处理表重复记录(查询和删除)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--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)if not object_id('Tempdb..#T') is null drop table #TGoCreate table #T([ID] int,[Name] nvarchar(1),[Memo] nvarchar(2))Insert #Tselect 1,N'A',N'A1' union allselect 2,N'A',N'A2' union allselect 3,N'A',N'A3' union allselect 4,N'B',N'B1' union allselect 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 A14 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 A35 B B2(2 行受影响)*/--2、删除重复记录有大小关系时,保留大或小其中一个记录--> --> (Roy)生成if not object_id('Tempdb..#T') is null drop table #TGoCreate table #T([ID] int,[Name] nvarchar(1),[Memo] nvarchar(2))Insert #Tselect 1,N'A',N'A1' union allselect 2,N'A',N'A2' union allselect 3,N'A',N'A3' union allselect 4,N'B',N'B1' union allselect 5,N'B',N'B2'Go--I、Name相同ID最小的记录(推荐用1,2,3),保留最小一条方法1:delete a from #T a where exists(select 1 from #T where Name=a.Name and ID<a.ID)方法2:delete a from #T a left join (select min(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID where b.Id is null方法3:delete a from #T a where ID not in (select min(ID) from #T where Name=a.Name)方法4(注:ID为唯一时可用):delete a from #T a where ID not in(select min(ID)from #T group by Name)方法5:delete a from #T a where (select count(1) from #T where Name=a.Name and ID<a.ID)>0方法6:delete a from #T a where ID<>(select top 1 ID from #T where Name=a.name order by ID)方法7:delete a from #T a where ID>any(select ID from #T where Name=a.Name)select * from #T生成结果:/*ID Name Memo----------- ---- ----1 A A14 B B1(2 行受影响)*/--II、Name相同ID保留最大的一条记录:方法1:delete a from #T a where exists(select 1 from #T where Name=a.Name and ID>a.ID)方法2:delete a from #T a left join (select max(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID where b.Id is null方法3:delete a from #T a where ID not in (select max(ID) from #T where Name=a.Name)方法4(注:ID为唯一时可用):delete a from #T a where ID not in(select max(ID)from #T group by Name)方法5:delete a from #T a where (select count(1) from #T where Name=a.Name and ID>a.ID)>0方法6:delete a from #T a where ID<>(select top 1 ID from #T where Name=a.name order by ID desc)方法7:delete a from #T a where ID<any(select ID from #T where Name=a.Name)select * from #T/*ID Name Memo----------- ---- ----3 A A35 B B2(2 行受影响)*/--3、删除重复记录没有大小关系时，处理重复值--> --> (Roy)生成 if not object_id('Tempdb..#T') is null drop table #TGoCreate table #T([Num] int,[Name] nvarchar(1))Insert #Tselect 1,N'A' union allselect 1,N'A' union allselect 1,N'A' union allselect 2,N'B' union allselect 2,N'B'Go方法1:if object_id('Tempdb..#') is not null drop table #Select distinct * into # from #T--排除重复记录结果集生成临时表#truncate table #T--清空表insert #T select * from # --把临时表#插入到表#T中--查看结果select * from #T/*Num Name----------- ----1 A2 B(2 行受影响)*/--重新执行测试数据后用方法2方法2:alter table #T add ID int identity--新增标识列godelete a from #T a where exists(select 1 from #T where Num=a.Num and Name=a.Name and ID>a.ID)--只保留一条记录goalter table #T drop column ID--删除标识列--查看结果select * from #T/*Num Name----------- ----1 A2 B(2 行受影响)*/--重新执行测试数据后用方法3方法3:declare Roy_Cursor cursor local forselect count(1)-1,Num,Name from #T group by Num,Name having count(1)>1declare @con int,@Num int,@Name nvarchar(1)open Roy_Cursorfetch next from Roy_Cursor into @con,@Num,@Namewhile @@Fetch_status=0begin set rowcount @con; delete #T where Num=@Num and Name=@Name set rowcount 0; fetch next from Roy_Cursor into @con,@Num,@Nameendclose Roy_Cursordeallocate Roy_Cursor--查看结果select * from #T/*Num Name----------- ----1 A2 B(2 行受影响)*/
[解决办法]
- SQL code
select max(hotelname),roomType, max(hotelid),max(hoteladdress), sum(isnull(ordercost,0)) as ordertotal from HotelOroder order by hotelid desc group by roomType
[解决办法]
- SQL code
--去除重复列，指定那个表的那个列就可以select a.id from a inner join b on a.id=b.id
[解决办法]
- SQL code
--按某一字段分组取最大(小)值所在行的数据--(爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开) 2007-10-23于浙江杭州)/*数据如下：name val memoa 2 a2(a的第二个值)a 1 a1--a的第一个值a 3 a3:a的第三个值b 1 b1--b的第一个值b 3 b3:b的第三个值b 2 b2b2b2b2b 4 b4b4b 5 b5b5b5b5b5*/--创建表并插入数据：create table tb(name varchar(10),val int,memo varchar(20))insert into tb values('a', 2, 'a2(a的第二个值)')insert into tb values('a', 1, 'a1--a的第一个值')insert into tb values('a', 3, 'a3:a的第三个值')insert into tb values('b', 1, 'b1--b的第一个值')insert into tb values('b', 3, 'b3:b的第三个值')insert into tb values('b', 2, 'b2b2b2b2')insert into tb values('b', 4, 'b4b4')insert into tb values('b', 5, 'b5b5b5b5b5')go--一、按name分组取val最大的值所在行的数据。--方法1：select a.* from tb a where val = (select max(val) from tb where name = a.name) order by a.name--方法2：select a.* from tb a where not exists(select 1 from tb where name = a.name and val > a.val)--方法3：select a.* from tb a,(select name,max(val) val from tb group by name) b where a.name = b.name and a.val = b.val order by a.name--方法4：select a.* from tb a inner join (select name , max(val) val from tb group by name) b on a.name = b.name and a.val = b.val order by a.name--方法5select a.* from tb a where 1 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name/*name val memo ---------- ----------- -------------------- a 3 a3:a的第三个值b 5 b5b5b5b5b5*/--二、按name分组取val最小的值所在行的数据。--方法1：select a.* from tb a where val = (select min(val) from tb where name = a.name) order by a.name--方法2：select a.* from tb a where not exists(select 1 from tb where name = a.name and val < a.val)--方法3：select a.* from tb a,(select name,min(val) val from tb group by name) b where a.name = b.name and a.val = b.val order by a.name--方法4：select a.* from tb a inner join (select name , min(val) val from tb group by name) b on a.name = b.name and a.val = b.val order by a.name--方法5select a.* from tb a where 1 > (select count(*) from tb where name = a.name and val < a.val) order by a.name/*name val memo ---------- ----------- -------------------- a 1 a1--a的第一个值b 1 b1--b的第一个值*/--三、按name分组取第一次出现的行所在的数据。select a.* from tb a where val = (select top 1 val from tb where name = a.name) order by a.name/*name val memo ---------- ----------- -------------------- a 2 a2(a的第二个值)b 1 b1--b的第一个值*/--四、按name分组随机取一条数据。select a.* from tb a where val = (select top 1 val from tb where name = a.name order by newid()) order by a.name/*name val memo ---------- ----------- -------------------- a 1 a1--a的第一个值b 5 b5b5b5b5b5*/--五、按name分组取最小的两个(N个)valselect a.* from tb a where 2 > (select count(*) from tb where name = a.name and val < a.val ) order by a.name,a.valselect a.* from tb a where val in (select top 2 val from tb where name=a.name order by val) order by a.name,a.valselect a.* from tb a where exists (select count(*) from tb where name = a.name and val < a.val having Count(*) < 2) order by a.name,a.val/*name val memo ---------- ----------- -------------------- a 1 a1--a的第一个值a 2 a2(a的第二个值)b 1 b1--b的第一个值b 2 b2b2b2b2*/--六、按name分组取最大的两个(N个)valselect a.* from tb a where 2 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name,a.valselect a.* from tb a where val in (select top 2 val from tb where name=a.name order by val desc) order by a.name,a.valselect a.* from tb a where exists (select count(*) from tb where name = a.name and val > a.val having Count(*) < 2) order by a.name , a.val/*name val memo ---------- ----------- -------------------- a 2 a2(a的第二个值)a 3 a3:a的第三个值b 4 b4b4b 5 b5b5b5b5b5*/--七，如果整行数据有重复，所有的列都相同。/*数据如下：name val memoa 2 a2(a的第二个值)a 1 a1--a的第一个值a 1 a1--a的第一个值a 3 a3:a的第三个值a 3 a3:a的第三个值b 1 b1--b的第一个值b 3 b3:b的第三个值b 2 b2b2b2b2b 4 b4b4b 5 b5b5b5b5b5*/--在sql server 2000中只能用一个临时表来解决，生成一个自增列，先对val取最大或最小，然后再通过自增列来取数据。--创建表并插入数据：create table tb(name varchar(10),val int,memo varchar(20))insert into tb values('a', 2, 'a2(a的第二个值)')insert into tb values('a', 1, 'a1--a的第一个值')insert into tb values('a', 1, 'a1--a的第一个值')insert into tb values('a', 3, 'a3:a的第三个值')insert into tb values('a', 3, 'a3:a的第三个值')insert into tb values('b', 1, 'b1--b的第一个值')insert into tb values('b', 3, 'b3:b的第三个值')insert into tb values('b', 2, 'b2b2b2b2')insert into tb values('b', 4, 'b4b4')insert into tb values('b', 5, 'b5b5b5b5b5')goselect * , px = identity(int,1,1) into tmp from tbselect m.name,m.val,m.memo from( select t.* from tmp t where val = (select min(val) from tmp where name = t.name)) m where px = (select min(px) from( select t.* from tmp t where val = (select min(val) from tmp where name = t.name)) n where n.name = m.name)drop table tb,tmp/*name val memo---------- ----------- --------------------a 1 a1--a的第一个值b 1 b1--b的第一个值(2 行受影响)*/--在sql server 2005中可以使用row_number函数，不需要使用临时表。--创建表并插入数据：create table tb(name varchar(10),val int,memo varchar(20))insert into tb values('a', 2, 'a2(a的第二个值)')insert into tb values('a', 1, 'a1--a的第一个值')insert into tb values('a', 1, 'a1--a的第一个值')insert into tb values('a', 3, 'a3:a的第三个值')insert into tb values('a', 3, 'a3:a的第三个值')insert into tb values('b', 1, 'b1--b的第一个值')insert into tb values('b', 3, 'b3:b的第三个值')insert into tb values('b', 2, 'b2b2b2b2')insert into tb values('b', 4, 'b4b4')insert into tb values('b', 5, 'b5b5b5b5b5')goselect m.name,m.val,m.memo from( select * , px = row_number() over(order by name , val) from tb) m where px = (select min(px) from( select * , px = row_number() over(order by name , val) from tb) n where n.name = m.name)drop table tb/*name val memo---------- ----------- --------------------a 1 a1--a的第一个值b 1 b1--b的第一个值(2 行受影响)*/
[解决办法]
- SQL code
建议你提供详细的资料：例如表的结构，表之间的关系，测试数据，相关算法及需要的结果。这样有助于我们理解你的意思，更主要的是能尽快让你获得答案或解决问题的方法。
[解决办法]
楼上两位大师太牛了，
[解决办法]
试试用distinct，这个函数专门除去重复列，但是它又不好的一点的是，只要你指定的那一列有相同的数据，它只会取其中一个值，在查询某些具体数字的数据时，不推荐使用。实例：select a.id ,distinct(b.name) from a,b where a.id=b.id