大家进来讨论一下，这个update带逗号的语句怎么会结果不对

Question

declare @CCC varchar(20)这个字段长度限制了

Answer 1

create table S_Temp(id int,ccc varchar(500))
go
insert into S_Temp values(1,'222')
insert into S_Temp values(2,'200')
go
select * from S_Temp
/*
结果集：
id  CCC
1    222
2    200
*/go
--我创建一个触发器来显示插进去的数据到底是什么
create trigger S_Insert
on S_Temp for update
as
begin
  declare @Str varchar(500)
  select @Str = ccc from inserted
  select @Str
end
go---注意@CCC字段长度
declare @CCC varchar(2000)
set @CCC = '222,222,111,134,314,54,456,7536,245,245,7653,245,7565,75,76,2,245,134,134,64,45,5765,456,245,7653,13'
--select len(@CCC)这里查出来@CCC的长度是100
update S_Temp set ccc = @CCC where iD = 1
/*
触发器中的结果集
无列名
222,222,111,134,314,
*/go
select * from S_Temp
/*
结果集：
id          ccc                                                                                                                                                                                                                                                              
----------- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 
1           222,222,111,134,314,54,456,7536,245,245,7653,245,7565,75,76,2,245,134,134,64,45,5765,456,245,7653,13
2           200（所影响的行数为 2 行）*/go
drop trigger S_Insert
go
drop table S_Temp