MySQL基础，聚合函数查询语句详解

电脑

MySQL

Navicat等可视化管理工具

测试用例数据

1.COUNT(<字段名>|*)：返回查询结果中记录行的总数COUNT(<*>)：返回表查询结果中的总行数，不管是否有空值COUNT(<字段名>)：返回字段查询结果中的总行数，忽略空值的行示例1：SELECT COUNT(*) FROM study_1;示例2：SELECT COUNT(sex) FROM study_1;示例3：结合GROUP BY分组统计查询结果行数数据SELECT GROUP_CONCAT(name) as names,sex,COUNT(*) FROM study_1 GROUP BY sex

2.SUM(<字段名>)：返回指定字段列的总和示例SELECT SUM(age) FROM study_1;示例2：结合GROUP BY分组统计字段和数据SELECT GROUP_CONCAT(name) as names,sex,SUM(age) FROM study_1 GROUP BY sex;

3.AVG(<字段名>)：对指定字段求和，再计算平均值示例SELECT AVG(age) FROM study_1;示例2：结合GROUP BY分组统计平均值数据SELECT GROUP_CONCAT(name) as names,sex,AVG(age) FROM study_1 GROUP BY sex;

4.MAX(<字段名>)，MIN(<最小值>)：返回指定字段的最大值，最小值示例1：SELECT MAX(age) FROM study_1;示例2：结合GROUP BY分组统计最大值数据SELECT GROUP_CONCAT(name) as names,sex,MAX(age) FROM study_1 GROUP BY sex;示例3：SELECT MIN(age) FROM study_1;示例4：结合GROUP BY分组统计最小值数据SELECT GROUP_CONCAT(name) as names,sex,MIN(age) FROM study_1 GROUP BY sex;