if(condition, a, b)
select sum(if(user_id>0, 1, 0)) as reigistered_count from order
case when condition then [A] else [B] end
select case grade>9 then '初中' else '小学' end as grade from student
2022-12-02 23:12:58
select sum(if(user_id>0, 1, 0)) as reigistered_count from order
select case grade>9 then '初中' else '小学' end as grade from student
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