SQL 自定义函数实例

---------------------------------sql server多行数据拼接
---------------------------------------

create table aaa(id int,typ varchar(20),code varchar(10))

insert into aaa values(1,'铅笔','0001')

insert into aaa values(2,'铅笔','0002')

insert into aaa values(3,'铅笔','0003')

insert into aaa values(4,'钢笔','0004')

insert into aaa values(5,'钢笔','0005')

insert into aaa values(6,'钢笔','0004')

insert into aaa values(7,'圆珠笔','0007')

insert into aaa values(8,'圆珠笔','0008')

insert into aaa values(9,'圆珠笔','0007')

----drop table aaa

-- select * from aaa

select code from aaa  where typ='铅笔'

select code from aaa  where typ='钢笔' group by
code

--需求结果:

--类型    汇总

--钢笔 0004,0005

--铅笔 0001,0002,0003

--圆珠笔  0007,0008

---1.使用了游标的自定义函数

drop function GetCode

create function GetCode(@typ varchar(20))

returns varchar(30)

as

begin

 declare @code varchar(10)

 declare @temp varchar(30)

 declare @num int

 declare mycur cursor for (select code from aaa
where typ=@typ group by code)

 open mycur

 fetch next from mycur into @code

 set @num=0

 while @@fetch_status=0

 begin

  if @num=0

  begin 

   set
@temp=@code

  end

  else

  begin

   select
@temp=@temp+'、'+@code

  end

  set
@num=@num+1  

  fetch next from mycur into
@code

 end

 close mycur

 deallocate mycur

 return @temp

end

select aaa.typ as 类型,dbo.GetCode(aaa.typ)as 汇总

from aaa group by aaa.typ

---2.用自定义函数做的

create function GetCode(@typ varchar(20))

returns nvarchar(200)

as

begin

 declare @str1 varchar(50)

 set @str1=''

 select @str1=@str1+'、'+code from aaa where
typ=@typ group by code

 select @str1=right(@str1,len(@str1)-1)

 --或select @str1=@str1+code+'、' from aaa where
typ=@typ group by code

 --select @str1=left(@str1,len(@str1)-1)

 return @str1

end

-- drop function GetCode

select typ,dbo.GetCode(typ) from aaa group by typ

-- select * from aaa

结果:

typ (无列名)

钢笔 0004、0005

铅笔 0001、0002、0003

圆珠笔 0007、0008