模糊查询与分组查询II

模糊查询与分组查询

统计数据

采用sum计算总和

计算平均数

查询最大值和最小值

***源代码***
-- SELECT COUNT(*)AS 总数据 FROM studentinfo
-- SELECT SUM(age) AS 总年龄 FROM studentinfo
-- SELECT AVG(age) AS 平均年龄 FROM studentinfo
SELECT MIN(age),MAX(age) FROM studentinfo
SELECT * FROM studentinfo WHERE age=(SELECT MAX(age) FROM studentinfo)