请帮我写一个sql好吗?
表:GuanCaoZuoJiLu
caozuoid,guanid,inittime
给出一个时间点后.以guanid分组,找出每组中,与这个时间差最小的记录集.
如:
caozuoid,guanid, inittime
1 1 2008-2-26 15:15
2 1 2008-2-26 15:15
3 2 2008-2-26 15:15
4 2 2008-2-26 15:15
给一个时间点:2008-2-26 15:14
我想得到两条记录:
caozuoid,guanid, inittime
1 1 2008-2-26 15:15
3 2 2008-2-26 15:15
表:GuanCaoZuoJiLu
caozuoid,guanid,inittime
给出一个时间点后.以guanid分组,找出每组中,与这个时间差最小的记录集.
如:
caozuoid,guanid, inittime
1 1 2008-2-26 15:15
2 1 2008-2-26 15:15
3 2 2008-2-26 15:15
4 2 2008-2-26 15:15
给一个时间点:2008-2-26 15:14
我想得到两条记录:
caozuoid,guanid, inittime
1 1 2008-2-26 15:15
3 2 2008-2-26 15:15
(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')
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)
*/
from tb a
where not exists(select 1 from tb where a.guanid=guanid and inittime>a.initime)
但是我还是不会写...
--都理解错楼主的意思了吧
给出一个时间点后.以guanid分组,找出每组中,与这个时间差最小的记录集.
---------------------------------------------------
declare @date datetime
set @date=''
select * from GuanCaoZuoJiLu a where not exists
(select 1 from GuanCaoZuoJiLu where guanid=a.guanid and abs(inittime-@date)<abs(a.inittime-@date)
一个guanid出一条记录.
有多少个guanid就有多少条记录..
再说一次.sql中计算时间差用"datediff"...
我自己写不出来..还是写不出来...
表:GuanCaoZuoJiLu
caozuoid,guanid,inittime
给出一个时间点后.以guanid分组,找出每组中,与这个时间差最小的记录集.
如:
caozuoid,guanid, inittime
1 1 2008-2-26 15:15
2 1 2008-2-26 15:15
3 2 2008-2-26 15:15
4 2 2008-2-26 15:15
给一个时间点:2008-2-26 15:14
我想得到两条记录:
caozuoid,guanid, inittime
1 1 2008-2-26 15:15
3 2 2008-2-26 15:15-----------------------------------------------
时间都一样,咋取最小?
当时间差一样时,取caozuoid小的那条记录...
(
select guanid , dt = min(abs(datediff(ss,inittime,'2008-2-26 15:14'))) from tb group by guanid
) n
where m.guanid = n.guanid and abs(datediff(ss,inittime,'2008-2-26 15:14')) = n.dt
insert into tb values(1, 1, '2008-2-26 15:15')
insert into tb values(2, 1, '2008-2-26 15:15')
insert into tb values(3, 2, '2008-2-26 15:15')
insert into tb values(4, 2, '2008-2-26 15:15')
go
select t1.* from
(
select m.* from tb m,
(
select guanid , dt = min(abs(datediff(ss,inittime,'2008-2-26 15:14'))) from tb group by guanid
) n
where m.guanid = n.guanid and abs(datediff(ss,inittime,'2008-2-26 15:14')) = n.dt
) t1 where caozuoid = (
select min(caozuoid) from
(
select m.* from tb m,
(
select guanid , dt = min(abs(datediff(ss,inittime,'2008-2-26 15:14'))) from tb group by guanid
) n
where m.guanid = n.guanid and abs(datediff(ss,inittime,'2008-2-26 15:14')) = n.dt
) t2 where t2.guanid = t1.guanid
)
drop table tb/*
caozuoid guanid inittime
----------- ----------- ------------------------------------------------------
1 1 2008-02-26 15:15:00.000
3 2 2008-02-26 15:15:00.000（所影响的行数为 2 行）
*/
Create table ttt(caozuoid int identity,guanid int,inittime datetime)
insert into ttt select 1,'2008-2-26 15:15'
insert into ttt select 1,'2008-2-26 17:15'
insert into ttt select 2,'2008-2-27 15:15'
insert into ttt select 2,'2008-2-28 15:15' declare @t datetime
set @t='2008-2-26 15:14'select a.caozuoid,guanid,inittime from (
select * ,abs(datediff(ss,@t,inittime)) as cdate from ttt ) a
where not exists(select 1 from (
select * ,abs(datediff(ss,@t,inittime)) as cdate from ttt ) b
where a.guanid=b.guanid and a.cdate>b.cdate )caozuoid guanid inittime
----------- ----------- -----------------------
1 1 2008-02-26 15:15:00.000
3 2 2008-02-27 15:15:00.000(2 行受影响)
完善下：Create table ttt(caozuoid int identity,guanid int,inittime datetime)
insert into ttt select 1,'2008-2-26 15:15'
insert into ttt select 1,'2008-2-26 15:15'
insert into ttt select 2,'2008-2-26 15:15'
insert into ttt select 2,'2008-2-26 15:15' declare @t datetime
set @t='2008-2-26 15:14'select a.caozuoid,guanid,inittime from (
select * ,abs(datediff(ss,@t,inittime)) as cdate from ttt ) a
where not exists(select 1 from (
select * ,abs(datediff(ss,@t,inittime)) as cdate from ttt ) b
where a.guanid=b.guanid and a.cdate>b.cdate )
and caozuoid in (select min(caozuoid) from (
select * ,abs(datediff(ss,@t,inittime)) as cdate from ttt ) c
where a.cdate=c.cdate and a.guanid=c.guanid
)caozuoid guanid inittime
----------- ----------- -----------------------
1 1 2008-02-26 15:15:00.000
3 2 2008-02-26 15:15:00.000(2 行受影响)