qq_40233706的博客

1.查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数select * from(select * from sc where cid="01")as t1inner join(select * from sc where cid="02")as t2on t1.sid=t2.sidinner join student as con c.sid=t1.sidwh...

1.查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数1.1 查询同时存在" 01 "课程和" 02 "课程的情况1.2 查询存在" 01 "课程但可能不存在" 02 "课程的情况(不存在时显示为 null )1.3 查询不存在" 01 "课程但存在" 02 "课程的情况...