日期:2014-05-17  浏览次数:20532 次

为实现union,想为其中一个表添加一个字段
select ID,
  Name as visitername,
  date as visitedate,
 Avatar(多出的)

from tab1 
union
select ID,
  Name as visitername,
  CreateDate as visitedate 
 from tab2
想在tab2里添加一个Avatar字段,类型是nvarchar(MAX),就相当于添加了一个和tab1里一样的字段:Avatar。并自动为填充“NULL”值
菜鸟,刚接触这些,问题比较多,之前的帖子还没结,现在有出现新的问题了。往CSDN里前辈指点指点晚辈呀。。

------解决方案--------------------
select ID,
Name as visitername,
date as visitedate,
 Avatar(多出的)

from tab1
union
select ID,
Name as visitername,
CreateDate as visitedate,
Null 
 from tab2

------解决方案--------------------
探讨

select ID,
Name as visitername,
date as visitedate,
Avatar(多出的)

from tab1
union
select ID,
Name as visitername,
CreateDate as visitedate,
Null
from tab2

------解决方案--------------------
SQL code

select 
    ID,Name as visitername,date as visitedate,Avatar
from tab1  
union all --建议使用union all ,因为union把重复的去掉了。
select 
    ID,Name,CreateDate,null  --多余的字段用null对应即可。(上面有as 别名了,下面不需要了)
from tab2