查询树型表函数的问题，崩溃啊

[yunhaiC QQ654777694]

CREATE function f_pid1(@id int,@tablename varchar(30)) returns varchar(100)
as
begin
  declare @re_str as varchar(100)
  set @re_str = ''
  select @re_str = name from @tablename where id = @id
  while exists (select 1 from @tablename where id = @id and pid is not null)
    begin
      select @id = b.id , @re_str = b.name + ',' + @re_str from @tablename a , @tablename b where a.id = @id and a.pid = b.id
    end
  return @re_str
end

他说我没声明@tablename,这个是传过来的参数啊，郁闷，到底怎么改，也有网友说用exec动态执行，但是我改来改去还是有bug，请教啊

CREATE function f_pid1(@id int,@tablename varchar(20)) returns varchar(100)
as
begin
  declare @re_str as varchar(100)
  set @re_str = ''
  exec('select '+@re_str+' = name from '+@tablename+' where id = '+rtrim(@id))
  exec('while exists (select 1 from tb where id = '+rtrim(@id)+' and pid is not null)
    begin
      select '+rtrim(@id)+' = b.id , '+@re_str+' = b.name + '','' + '+@re_str+' from '+@tablename+' a , tb b where a.id = '+rtrim(@id)+' and a.pid = b.id
    end')
  return @re_str
end

[Xiao_Ai_Mei]

函数里没法执行动态
改存储过程吧

[yunhaiC QQ654777694]

[Quote=引用 1 楼 xiao_ai_mei 的回复:]

函数里没法执行动态
改存储过程吧
[/Quote]
但是我可能有其他表也需要用这个功能，我不能每次都要根据各个表写同样的功能啊，所以还是需要放在函数里面

[AcHerat]

存储过程也可以加参数！

[yunhaiC QQ654777694]

[Quote=引用 3 楼 acherat 的回复:]

存储过程也可以加参数！
[/Quote]

create Procedure  f_pid1
@id int,
@tablename varchar(30),
@re_str varchar(100) output
as
begin
  set @re_str = ''
  select @re_str = name from @tablename where id = @id
  while exists (select 1 from @tablename where id = @id and pid is not null)
    begin
      select @id = b.id , @re_str = b.name + ',' + @re_str from @tablename a , @tablename b where a.id = @id and a.pid = b.id
    end
end

还是不行

[xiangchao107]

有高手解决了没有啊，正需要这方面的东西

[yunhaiC QQ654777694]

至今没有完全解决

[wokelv]

>>>> 函数里没法执行动态

那数据库里的 内部函数(Avg, Sum, Count等)怎么实现的..
求解..