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select MAX(grade) as ‘最高分’, MIN(grade) as ‘最低分’,
AVG(grade) as ’ 平均分’,COUNT(*) as ‘学生数量’, from t_score where cno =‘CO1’select MAX(grade) as ‘最高分’, MIN(grade) as ‘最低分’,
AVG(grade) as ’ 平均分’,COUNT(*) as ‘学生数量’, from t_score GROUP BY cno例3
聚合函数: 最大值max,最小值min,平均值avg,求和sum,总数count。 分组group by 分组条件:group by having…转载地址:http://fuqzi.baihongyu.com/