在MySQL和Oracle中实现行合ƈ
http://www.aygfsteel.com/rain1102/archive/2009/06/24/283867.html
SQL Server
--SQL2005中的Ҏ2
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go
select id, [values]=stuff((select ','+[value] from tb t where id=tb.id
for xml path('')), 1, 1, '')
from tb
group by id
/*
id values
----------- --------------------
1 aa,bb
2 aaa,bbb,ccc
(2 row(s) affected)
*/
drop table tb
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go
select id, [values]=stuff((select ','+[value] from tb t where id=tb.id
for xml path('')), 1, 1, '')
from tb
group by id
/*
id values
----------- --------------------
1 aa,bb
2 aaa,bbb,ccc
(2 row(s) affected)
*/
drop table tb
MySQL
select name , group_concat(email order by email separator ", ") as email from student group by name
Oracle
如果以上效果惛_Oracle中显C? 则比较复杂点? 因ؓOracle中没有行合ƈ函数, 则需要用sys_connect_by_path()来实? 代码如下:
select name, ltrim(sys_connect_by_path(email,','),',') email from(
select name,email,
row_number() over(partition by name order by email) rn,
count(*) over(partition by name) cnt
from student
) where level = cnt
start with rn = 1
connect by prior name = name and prior rn + 1 = rn
select name, ltrim(sys_connect_by_path(email,','),',') email from(
select name,email,
row_number() over(partition by name order by email) rn,
count(*) over(partition by name) cnt
from student
) where level = cnt
start with rn = 1
connect by prior name = name and prior rn + 1 = rn
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今天做项目时候就遇到q问?br /> 中文提示“找不到相应的L?#8221;
q时候请查数据库服务器上 MySql.Data.dll 文g版本和项?bin 目录下的版本是否一致?/p>
如果q程L版本?6.0.3
而项目引用的?5.0.3
则会出现以上的错误提C?/p>
但是如果本机L上版本是 6.0.3
即ə目引用的是 5.0.3
也能正常q接数据库，不清楚是什么原?/p>
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SQL~码规范(攉) http://hi.baidu.com/rambochow/blog/item/3ebcbb3db3758903bba16743.html
1.书写格式 
7.Ҏ据库表操作的Ҏ要求