判断数据库表字段是否为null值，采用is null
use UserCenter
go
select * from AccountDetails
1、判断一个字段是否为null值，进行查询：
update AccountDetails set ProjectCode ='w88' where ProjectCode is null
2、这一种写法是错误的
update AccountDetails set ProjectCode ='w88' where ProjectCode = null
use UserCenter
go
select * from AccountDetails
1、判断一个字段是否为null值，进行查询：
update AccountDetails set ProjectCode ='w88' where ProjectCode is null
2、这一种写法是错误的
update AccountDetails set ProjectCode ='w88' where ProjectCode = null
