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select a.xh,a.xm,
case when b.yw-b.ss<=0 then '差'
else '良'
end
as cj
from b1 a inner join b2 b on a.xh=b.xh
select a.xh,a.xm,
case when b.yw+b.ss<120 then '差'
when b.yw+b.ss<80 then '良'
else '优'
end
as cj
from b1 a inner join b2 b on a.xh=b.xh
/*
标题:简单数据拆分(version 2.0)
作者:爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)
时间:2010-05-07
地点:重庆航天职业学院
描述:
有表tb, 如下:
id value
----------- -----------
1 aa,bb
2 aaa,bbb,ccc
欲按id,分拆value列, 分拆后结果如下:
id value
----------- --------
1 aa
1 bb
2 aaa
2 bbb
2 ccc
*/
--1. 旧的解决方法(sql server 2000)
create table tb(id int,value varchar(30))
insert into tb values(1,'aa,bb')
insert into tb values(2,'aaa,bbb,ccc')
go
--方法1.使用临时表完成
SELECT TOP 8000 id = IDENTITY(int, 1, 1) INTO # FROM syscolumns a, syscolumns b
SELECT A.id, value = SUBSTRING(A.[value], B.id, CHARINDEX(',', A.[value] + ',', B.id) - B.id)
FROM tb A, # B
WHERE SUBSTRING(',' + A.[value], B.id, 1) = ','
DROP TABLE #
--方法2.如果数据量小,可不使用临时表
select a.id , value = substring(a.value , b.number , charindex(',' , a.value + ',' , b.number) - b.number)
from tb a join master..spt_values b
on b.type='p' and b.number between 1 and len(a.value)
where substring(',' + a.value , b.number , 1) = ','
--2. 新的解决方法(sql server 2005)
create table tb(id int,value varchar(30))
insert into tb values(1,'aa,bb')
insert into tb values(2,'aaa,bbb,ccc')
go
--方法1.使用xml完成
SELECT A.id, B.value FROM
(
SELECT id, [value] = CONVERT(xml,'<root><v>' + REPLACE([value], ',', '</v><v>') + '</v></root>') FROM tb
) A OUTER APPLY
(
SELECT value = N.v.value('.', 'varchar(100)') FROM A.[value].nodes('/root/v') N(v)
) B
--方法2.使用CTE完成
;with tt as
(select id,[value]=cast(left([value],charindex(',',[value]+',')-1) as nvarchar(100)),Split=cast(stuff([value]+',',1,charindex(',',[value]+','),'') as nvarchar(100)) from tb
union all
select id,[value]=cast(left(Split,charindex(',',Split)-1) as nvarchar(100)),Split= cast(stuff(Split,1,charindex(',',Split),'') as nvarchar(100)) from tt where split>''
)
select id,[value] from tt order by id option (MAXRECURSION 0)
DROP TABLE tb
/*
id value
----------- ------------------------------
1 aa
1 bb
2 aaa
2 bbb
2 ccc
(5 行受影响)
*/
select
a.xh,a.xm,
case when isnull(b.yw,)-isnull(b.ss,0)<=0 then '差' else '良' end as cj
from
b1 a
left join b2 b on a.xh=b.xh
select
a.*,case when b.xh is not null AND b.yw-b.ss <=0 THEN '差 ' else '良 ' end
from b1 as a left join b2 as b on a.xh=b.xh
create table b1(xh int,xm varchar(10))
create table b2(xh int,yw int,ss int)
insert into b1 select 1,'张三'
insert into b1 select 2,'李四'
insert into b1 select 3,'王五'
insert into b2 select 1,40,50
go
select a.xh,a.xm,
case when b.yw-b.ss<=0 then '差'
else '良'
end
as cj
from b1 a left join b2 b on a.xh=b.xh
/*
xh xm cj
----------- ---------- ----
1 张三 差
2 李四 良
3 王五 良
(3 行受影响)
*/
go
drop table b1,b2