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  • 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

    //createConnection(哪台服务器, 用户名, 密码, 库)
    var db=mysql.createConnection({host: 'localhost', user: 'root', password: 'a123456789', database: '20181105'});
    4.关键字大小 字段加上 ` `

    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;

     

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  • 原文地址:https://www.cnblogs.com/tongbiao/p/9911633.html
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