Node connects to MySQL and encapsulates its implementation code for adding, deleting, modifying and checking

npm install mysql

    const mysql = require('mysql');
    
    let connection = mysql.createConnection({
        host : 'localhost',
        user : 'root', 
        password : 'password',
        database : 'test'
    });
 
connection.connect(function(err) {
  if (err) {
    console.error('Connection failed: ' + err.stack);
    return;
  }
 
  console.log('Connection successful id ' + connection.threadId);
});

connection.query('SELECT * FROM t_user WHERE username = "whg"', (err, results, fields) => {
    if(err){
        console.log(err);
    }
    console.log(results);
})

connection.query('INSERT INTO t_user(username, pass) VALUES(?, ?)',['whg', '123'], (err, results) => {
    if(err){
        console.log(err);
    }
    console.log(results);
})

connection.query('DELETE FROM t_user WHERE id = 1', (err, results) => {
    if(err){
        console.log(err);
    }
    console.log(results);
})

connection.query('UPDATE t_user SET pass = "321" WHERE username = "whg"', (err, results) => {
    if(err){
        console.log(err);
    }
    console.log(results);
})

connection.end(function(err) {
  
});
connection.destroy();

//Configure the link database parameters module.exports = {
    host : 'localhost',
    port : 3306, //Port number database : 'nodetest', //Database name user : 'root', //Database username password : '123456' //Database password };

let mysql = require('mysql'); //Introduce the mysql module var databaseConfig = require('./mysql.config'); //Introduce the data in the database configuration module //Exposing the method module.exports = {
    query : function (sql, params, callback) {
        //You need to create a connection each time you use it, and close the connection after the data operation is completed var connection = mysql.createConnection(databaseConfig);        
        connection.connect(function(err){
            if(err){
                console.log('Database connection failed');
                throw err;
            }
         //Start data operation//Pass in three parameters, the first parameter is the sql statement, the second parameter is the data required in the sql statement, and the third parameter is the callback function connection.query( sql, params, function(err,results,fields ){
           if(err){
                console.log('Data operation failed');
                throw err;
            }
            //Return the queried data to the callback function callback && callback(results, fields);
            //results is the result of the data operation, fields is some fields of the database connection //To stop connecting to the database, you must query the statement, otherwise, once this method is called, the connection will be stopped directly and the data operation will fail connection.end(function(err){
                  if(err){
                      console.log('Failed to close database connection!');
                      throw err;
                  }
              });
           });
       });
    }
};

var db = require('../model/mysql.js');
// Query example db.query('select * from t_user', [],function(result,fields){
    console.log('Query results:');
    console.log(result);
});
//Add instance var addSql = 'INSERT INTO websites(username,password) VALUES(?,?)';
var addSqlParams =['Mr. Gulu', '666'];
db.query(addSql,addSqlParams,function(result,fields){
    console.log('Added successfully')
})