T-SQL语句的"IS NOT NULL"部分无效

Question

这句话有什么问题？

SELECT ID, datediff("mi", Start, End) as Total 
FROM TimeTable
WHERE Total is not null

我收到错误"无效的列名称"

Answer 1

引用表达式,而不是别名.

SELECT ID, datediff("mi", Start, [End]) as Total 
FROM TimeTable
WHERE datediff("mi", Start, [End])  is not null

编辑,更新以防止使用END语法错误