我想让user_code,和 meter_num 他们组成的信息不能重复，也就是user_code和meter_num所对应的数据可以重复，但是他们两个不能同时对应：例如 user_code 对应的 123456  meter_num 对应的数为 65887 这条信息不能重复，就是user_code 对应的 123456  能和meter_num所对应其他数据组成其他信息
下面存储过程怎么改啊？
ALTER PROCEDURE [dbo].[create_newuser_new_meter_pro]
    @user_code char(12),@user_china_name char(20),@user_address varchar(100),@user_iden_num char(18),@user_tele char(20),@area_code  int,
             @addr_code int,@build_code int,@door_num int,@user_state char(4),    
             @meter_num char(10),@meter_type int,@price_code int,@diploid bigint,@alarm_min decimal(18,2),@alarm_max decimal(18,2),@meter_max decimal(18,2),@pur_max decimal(18,2),
             @over_zero_pow decimal(18,2),@pow_limit bigint,@user_type tinyint,@pre_pow decimal(18,2),
    @Rst int output
 AS   
    set nocount on 
             declare @@price_adjust_count int  
             set @@price_adjust_count=(select max(price_adjust_count) from price_info where price_code=@price_code and is_active='活动')
begin tran
             insert into user_info(user_code,user_china_name,user_address,user_iden_num,user_tele,area_code,addr_code,build_code,door_num,pur_count,pur_money,user_state,user_type)  values(@user_code,@user_china_name,@user_address,@user_iden_num,@user_tele,@area_code,@addr_code,@build_code,@door_num,0,0,@user_state,@user_type)
             /*新 修改 */
              if @@error<>0
     begin  
        rollback tran
        set @Rst=0
                           goto err_out
    end
             /*新 修改 */
              insert into user_meter_info values(@user_code,@meter_num,@user_state,1,@meter_type,@price_code,@@price_adjust_count,@diploid,0,0,0,0,0,1,@alarm_min,@alarm_max,@meter_max,@over_zero_pow,@pow_limit,@pur_max,@pre_pow,getdate(),null,@user_code,null,null);
commit tran
if @@error<>0
    begin  
        rollback tran
        set @Rst=0
    end
    set @Rst=1
err_out:




set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go


/****** Object:  Stored Procedure dbo.create_newuser_meter_pro    Script Date: 2007-11-9 09:52:38 ******/

/****** Object:  Stored Procedure dbo.create_newuser_meter_pro    Script Date: 2007-10-13 13:24:53 ******/
/*说明：
新建用户的新的电表信息，用于换表，新建用户的电表
*/
ALTER PROCEDURE [dbo].[create_newuser_meter_pro]
    @user_code char(12),@new_meter_num char(10),@old_meter_num  char(10),@meter_type int,@price_code int,@price_adjust_count int,@diploid bigint,@alarm_min decimal(18,2),@alarm_max decimal(18,2),@meter_max decimal(18,2),@pur_max decimal(18,2),
    @workid bigint,@oper_power decimal(18,2),@oper_date datetime,@old_diploid bigint,@change_reason varchar(50),@Rst int output
 AS
    set nocount on 
begin tran 
            declare @@meter_index int
            set @@meter_index=(select max(user_index) from user_meter_info where user_code=@user_code )
            set @@meter_index=@@meter_index+1
            update user_meter_info set in_use='未用' where user_code=@user_code and in_use='使用' and meter_num=@old_meter_num
/* 实际的换 表程序此处需要修改*/
            insert  user_meter_info values(@user_code,@new_meter_num,'换表',@@meter_index,@meter_type,@price_code,@price_adjust_count,@diploid,0,0,0,0,0,1,@alarm_min,@alarm_max ,@meter_max ,0,0,0,@pur_max,getdate(),null,null,null,null)
            insert  meter_change_info values(@workid,@user_code,@old_meter_num,@new_meter_num,@oper_power,@oper_date,@old_diploid,@diploid,@change_reason)
commit tran
if @@error<>0 
    begin 
        rollback tran 
        set @Rst=0
    end
    set @Rst=1