34,590
社区成员
发帖
与我相关
我的任务
分享
create table tb(编码 varchar(100),局编号 varchar(100),地址 varchar(100),日期 varchar(10),读数 decimal(9,2))
insert into tb
select '2000130741','DDZ031030','永怡花园怡和阁3幢704','2008-2-26',3250.32
union all select '2000130741','DDZ031030','永怡花园怡和阁3幢704','2008-2-27',3253.17
union all select '2000223283','DDZ031035','凯茵新城A12区B2幢701','2008-2-26',881.06
union all select '2000223283','DDZ031035','凯茵新城A12区B2幢701','2008-2-27',881.50
union all select '2000223285','DDZ031040','凯茵新城A12区F6幢102','2008-2-26',369.83
union all select '2000223285','DDZ031040','凯茵新城A12区F6幢102','2008-2-27',369.83
union all select '2000223285','DDZ031040','凯茵新城A12区F6幢102','2008-2-28',369.83
union all select '2000221567','DDZ031041 ','凯茵新城01区E型高层3座13层15A','2008-2-26',956.90
union all select '2000221567','DDZ031041 ','凯茵新城01区E型高层3座13层15A','2008-2-28',956.90
go
alter table tb add ID int identity(1,1)
go
delete tb where id not in
(
select max(id) as id from tb
inner join
(
select 编码,局编号,地址,max(读数)as 读数
from tb
group by 编码,局编号,地址
) y on tb.编码 = y.编码 and tb.局编号 = y.局编号 and tb.地址 = y.地址 and tb.读数 = y.读数
group by tb.编码,tb.局编号,tb.地址,tb.读数
)
alter table tb drop column ID
select * from tb;
drop table tb;
go
--按某一字段分组取最大(小)值所在行的数据
(爱新觉罗.毓华 2007-10-23于浙江杭州)
/*
数据如下:
name val memo
a 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 b2b2b2b2
b 4 b4b4
b 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5
select 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5
select 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)val
select a.* from tb a where 2 > (select count(*) from tb where name = a.name and val < a.val ) order by a.name,a.val
select 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.val
select 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
/*
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)val
select a.* from tb a where 2 > (select count(*) from tb where name = a.name and val > a.val ) order by a.name,a.val
select 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.val
select 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
/*
name val memo
---------- ----------- --------------------
a 2 a2(a的第二个值)
a 3 a3:a的第三个值
b 4 b4b4
b 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 memo
a 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 b2b2b2b2
b 4 b4b4
b 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')
go
select * , px = identity(int,1,1) into tmp from tb
select 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')
go
select 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)
*/
delete from 表 a where 读数 not in (select max(读数) from 表 where 局编号 = a.局编号)
create table tb(编码 varchar(100),局编号 varchar(100),地址 varchar(100),日期 varchar(10),读数 decimal(9,2))
insert into tb
select '2000130741','DDZ031030','永怡花园怡和阁3幢704','2008-2-26',3250.32
union all select '2000130741','DDZ031030','永怡花园怡和阁3幢704','2008-2-27',3253.17
union all select '2000223283','DDZ031035','凯茵新城A12区B2幢701','2008-2-26',881.06
union all select '2000223283','DDZ031035','凯茵新城A12区B2幢701','2008-2-27',881.50
go
select * from tb;
delete from tb where not exists(select 1 from tb t where t.局编号=tb.局编号 and t.读数 < tb.读数)
select * from tb;
go
drop table tb;
go
(4 行受影响)
编码 局编号 地址 日期 读数
---------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------- ---------- ---------------------------------------
2000130741 DDZ031030 永怡花园怡和阁3幢704 2008-2-26 3250.32
2000130741 DDZ031030 永怡花园怡和阁3幢704 2008-2-27 3253.17
2000223283 DDZ031035 凯茵新城A12区B2幢701 2008-2-26 881.06
2000223283 DDZ031035 凯茵新城A12区B2幢701 2008-2-27 881.50
(4 行受影响)
(2 行受影响)
编码 局编号 地址 日期 读数
---------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------- ---------- ---------------------------------------
2000130741 DDZ031030 永怡花园怡和阁3幢704 2008-2-27 3253.17
2000223283 DDZ031035 凯茵新城A12区B2幢701 2008-2-27 881.50
(2 行受影响)
delete tb from tb t where 读数 not in (select max(读数) from tb where 局编号 = t.局编号)