*.D.龙

摘要： 面试题1：怎么把这样一个表儿year month amount1991 1 1.11991 2 1.21991 3 1.31991 4 1.41992 1 2.11992 2 2.21992 3 2.31992 4 2.4查成这样一个结果year m1 m2 m3 m41991 1.1 1.2 1.3 1.41992 2.1 2.2 2.3 2.4 答案select year, (select amount from aaa m where month=1 and m.year=aaa.year) as m1,(select amount from aaa m where month=2 an 阅读全文