如何在SQL查询测试NULL

Question

string query = 
    "select User_name, User_Second_Choice 
    from tbl_User where User_Assigned_Project ='"+NULL+"'"; 

我尽量选择要更新的行，所以我如何改变User_Assigned_Project = ' “+ NULL +”'“;。

谢谢

Answer 1

使用IS NULL not'= NULL'

select User_name, User_Second_Choice 
from tbl_User where User_Assigned_Project IS NULL