NULL不是数值解决方法

declare @alive bit;set @alive = null;if @alive = 1 or @alive != 1    print 'Alive or Dead';else    print 'Huh? Neither alive nor dead';    if @[email protected]    PRINT 'It must equal itself, right?'ELSE    PRINT 'Not always. null does not equal null';    

declare @alive bit;set @alive = null;if @alive = 1 or @alive != 1    print 'Alive or Dead';else    print 'Huh? Neither alive nor dead';    if null is null    PRINT 'It must equal itself, right?'ELSE    PRINT 'Not always. null does not equal null';/*Huh? Neither alive nor deadIt must equal itself, right?
------解决方案--------------------
Null is woman's looks
------解决方案--------------------
null does not equal null
------解决方案--------------------
SQL code
What would be the output ?declare @a smallint set @a = 0 select nullif ( @a , '' )
------解决方案--------------------
NULL<>''
------解决方案--------------------

mark
------解决方案--------------------
null does not equal null!
null is null!
------解决方案--------------------
俺只会中文
NULL确实不能比较只能IS
------解决方案--------------------
改了配置已经可以比较哦
------解决方案--------------------
都是些外国人。呵呵  null是什么都没有的意思。所以由此所得 null就不是数字
------解决方案--------------------
 is null
------解决方案--------------------
其实楼主是拉晒英文呢
------解决方案--------------------
null=undefined value=未知


------解决方案--------------------
set ansi_nulls off后结果就不同了.
SQL code
set ansi_nulls offdeclare @alive bit;set @alive = null;if @alive = 1 or @alive != 1    print 'Alive or Dead';else    print 'Huh? Neither alive nor dead';    if @[email protected]    PRINT 'It must equal itself, right?'ELSE    PRINT 'Not always. null does not equal null';--> 结果Alive or DeadIt must equal itself, right?
------解决方案--------------------
null确实不能比较 但是可以通过 isnull转化在比较  isnull(字段,'')  如果是NULL则转化为 ‘’ 空字符串
------解决方案--------------------
探讨


引用:

其实楼主是拉晒英文呢


挂这么多牌牌，还欺负人么？
偶要是英文好，就不写一个汉字。

------解决方案--------------------
探讨


引用:

SQL code
What would be the output ?

declare @a smallint
set @a = 0
select nullif ( @a , '' )


这个更有意思


见识了。

------解决方案--------------------