自定义函数遇到的问题

[Hopeinwhere001]

例如

create Function GetFdesc (@Fdesc as varchar (20))
returns varchar(20)
as
begin
declare @Fdesc varchar (20)
select @Fdesc=Fdesc from T1 WEHRE Fdesc like @Fdesc
return @Fdesc
end

问题，Like 后怎么接参数?
我上面的写法不对,返回值为空

[水族杰纶]

create Function GetFdesc (@Fdesc as varchar (20))
returns varchar(20)
as  
begin
  declare @Fdesc varchar (20)
  select @Fdesc=Fdesc from T1 WEHRE Fdesc like '%'+@Fdesc+'%' 
  --or
  --select @Fdesc=Fdesc from T1 WEHRE Fdesc like '%'+@Fdesc
  --or
  --select @Fdesc=Fdesc from T1 WEHRE Fdesc like @Fdesc+'%'
  return @Fdesc
end