node.js中mysql模块使用

const mysql = require('mysql'); //先安装mysql模块 npm install mysql

/*let db = mysql.createConnection({host:'localhost',user:'root',password:'admin',port:3306, database:'mydatabase'});*/

//一般使用连接池方式
let db = mysql.createPool({host:'localhost',user:'root',password:'admin',port:3306, database:'mydatabase'}); //maxConnection:'10' 此为隐藏参数。默认10个链接，一般够用了


db.query('select * from user',(err,data)=>{
    if(err){
        console.log('错了',err);
    }
    console.log(data);
});

SQL：

1.增 INSERT

INSERT INTO 表 (字段列表) VALUES(值列表)
INSERT INTO user_table (ID, name, gender, chinese, math, english) VALUES(0, 'blue', '男', 35, 18, 29);

2.删 DELETE

DELETE FROM 表 WHERE 条件
DELETE FROM user_table WHERE ID=3;

3.改 UPDATE

UPDATE 表 SET 字段=值, 字段2=值2, ... WHERE 条件
UPDATE user_table SET chinese=100 WHERE ID=2;

4.查 SELECT

SELECT 字段列表 FROM 表 WHERE 条件
SELECT name, gender FROM user_table WHERE ID=2;