asp.net - 如何在 SQL 查询中测试 NULL

Question

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

我尝试选择要更新的行，所以我该如何更改 User_Assigned_Project = '"+NULL+"'";

谢谢你。

Answer 1

使用IS NULL而不是 '= NULL'

select User_name, User_Second_Choice 
from tbl_User where User_Assigned_Project IS NULL