定义函数的问题

[hmily1688]

CREATE function f_calc(@kehu_id varchar(20),@year int,@month int,@table_name varchar(30))
returns numeric
as
begin
declare @re numeric
declare @sql_str varchar(2000)
select @sql_str= 'select sum(consume_point) from'+@table_name
+' where kehu_id='''+@kehu_id+''' and ticket_year='+@year
+' and ticket_month='+@month
@re=exec(@sql_str)
return(@re)
end
应为表名不固定，所以想这样来传表变量
告诉我出错