mysql 基本
客户端: navicat-管理工具,
1.主键 : 唯一.性能高,
2.库-管理 表-存 字段 行
3.连接
01.INSERT INTO `user_table` (`ID`, `username`, `password`) VALUES(0, 'blue2', '987654');
02.SELECT * FROM `user_table`;
03.SELECT * FROM student_table GROUP BY class;
04.SELECT class,AVG(score) FROM student_table GROUP BY class;
05.SELECT class,MAX(score),MIN(score) FROM student_table GROUP BY class;
06.根据名字求和
SELECT name,SUM(price) FROM sales_table GROUP BY name;
07.排序 降序
SELECT name,SUM(price) FROM sales_table GROUP BY name ORDER BY SUM(price) DESC;
08.排序 升序
SELECT name,SUM(price) FROM sales_table GROUP BY name ORDER BY SUM(price) ASC;
09.删选 合并 排序 限制
SELECT * FROM student_table WHERE score>60 GROUP BY class ORDER BY COUNT(class) DESC LIMIT 2;