SQL 查询例子

student表                                     score 表
ID                                        ID
name                                      result
class
sex
age




1.查询名字叫‘小明’的成绩

select b.result from student a left join score b on a.ID=b.ID where a.name='小明'；


2.统计各班总成绩

select a.class,sum(b.result) from student a left join score b on a.ID=b.ID group by a.class;


3.查出A班成绩最高的同学的名字
select a.name from student a left join score b on a.ID=b.ID where a.class='A' and b.result in (select max(b.result)from student a left join score b on a.ID=b.ID where a.class='A' );