13题
select
sid,
avg(score) as avg_score,
sum(case cid when '01' then score else 0 end) as '01',
sum(case cid when '02' then score else 0 end) as '02',
sum(case cid when '03' then score else 0 end) as '03'
from sc
group by sid
order by avg(score) desc;
50道SQL练习题及答案与详细分析网上流传较广的50道SQL训练，奋斗了不知道多久终于写完了。前18道题的难度依次递增，从19题开始的后半部分算是循环练习和额外function的附加练习，难度恢复到普通状态。...