Question

SQL语句case怎么判断这个字段为空

case 某字段 when ? then '是空的' end
？处应该怎么写才能判断他是空的，才能给他赋值

Answer 1

select *,'结果'= case
when grade is null then '是空的' end

Answer 2

CASE WHEN 某字段 IS NULL THEN '是空的' END

Answer 3

case when isnull(某字段,'') = '' then ... end