CREATE TRIGGER TR_INSERTMPURTD05 ON [dbo].[PURTD] 
FOR INSERT
AS
DECLARE     @TD001 CHAR(4),
    @TD002 CHAR(11),
                    @TD003 CHAR(4),
                    @TD004 CHAR(20),
            @TC004 CHAR(10),
            @SL NUMERIC(16,6)
            
  
                   
BEGIN TRANSACTION
SET NOCOUNT ON
SELECT @TD001=TD001,@TD002=TD002,@TD004=TD004,@TD003=TD003 FROM INSERTED
SELECT @SL=SUM(TD008)-TD015 FROM PURTD WHERE TD004=@TD004 AND TD016='N' 

UPDATE PURTD SET UDF56=@SL WHERE TD001=@TD001 AND TD002=@TD002 AND TD003=@TD003
SET NOCOUNT OFF
COMMIT TRANSACTION 

消息 8120，级别 16，状态 1，过程 TR_INSERTMPURTD05，第 16 行
选择列表中的列 'PURTD.TD015' 无效，因为该列没有包含在聚合函数或 GROUP BY 子句中。

CREATE TRIGGER TR_INSERTMPURTD05 ON [dbo].[PURTD] 
FOR INSERT
AS
DECLARE     @TD001 CHAR(4),
    @TD002 CHAR(11),
                    @TD003 CHAR(4),
                    @TD004 CHAR(20),
            @TC004 CHAR(10),
            @SL NUMERIC(16,6)
            
  
                   
BEGIN TRANSACTION
SET NOCOUNT ON
SELECT @TD001=TD001,@TD002=TD002,@TD004=TD004,@TD003=TD003 FROM INSERTED
SELECT @SL=SUM(TD008)-TD015 FROM PURTD WHERE TD004=@TD004 AND TD016='N' --这句话有错
/*
如果楼主一定要这么写，那就得在后面出现group by TD015
*/

UPDATE PURTD SET UDF56=@SL WHERE TD001=@TD001 AND TD002=@TD002 AND TD003=@TD003
SET NOCOUNT OFF
COMMIT TRANSACTION

------解决方案--------------------
用1楼或3楼的方法,程序可以运行,但结果不同,另外,没有考虑到可以一次插入多条记录的情况,inserted表可以有多行的情形.

------解决方案--------------------
sum需要GROUP BY语句