题目:
结果:
参考https://bbs.fanruan.com/wenda/question/120856.html
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SELECT R1.类别, R1.月份, SUM(R2.Revenue)
FROM Revenue R1, Revenue R2
WHERE
R1.ID >= R2.ID
AND R1.类别 = R2.类别
GROUP BY R1.月份, R1.类别
ORDER BY R1.ID, R1.类别 , R1.月份;
因为字符串的比较出问题
你这个是考试题还是模拟题啊,考试题好像不能帮你回答的。。。