sql语句 case和sum 一起出现时怎么显示

如果FID是固定的只有1,2,3,4，可以用下面的sql实现 select MID, sum(case when fid = 1 then score else null end) score1, sum(case when fid = 2 then score else null end) score2, sum(case when fid = 3 then score else null end) score3, sum(case when fid = 4 then score else null end) score4 from tablename group by MID

没有group by，你的条件用到的字段都需要在Group By里出现

select sum(case 1 then result1 when 2 then result2 end) as result from table group by ?

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