node中实现与数据库的交互，实现增删改查操作

// 先npm init 初始化  然后下载  npm i mysql -S
let mysql = require("mysql")
// 创建链接
var connection = mysql.createConnection({
    host: ‘localhost‘,
    user: ‘root‘,
    password: ‘12345678‘,//数据库密码
    database: "4399"//数据库名称
});
// 打开链接
connection.connect();

var addSql = `INSERT INTO message(id,name,comment) VALUES (?,?,?)`;
        var addSqlParams = [query.id,query.name, query.comment]
        connection.query(addSql,addSqlParams, function (error, results, fields) {
            if (error) { console.log("失败"); }
            else {
                console.log(‘The solution is: ‘, results);
            }

        });
//关闭链接
connection.end();

var upSql = `update message set name = ?,comment = ? where id = ?`;
        var upSqlParams = [query.name, query.comment, idnum]
    //idnum为其他内容中赋予的值，当作id使用
        connection.query(upSql, upSqlParams, function (error, results, fields) {
            if (error) { console.log("失败"); }
            else {
                console.log(‘The solution is: ‘, results);
                console.log(query.id);
                console.log(query.name);
                console.log(query.comment);
            }

        });

connection.query(‘select * from message order by id desc‘, function (error, results, fields) {
                if (error) { console.log(error); }
                else {
                    // console.log(‘The solution is: ‘, results);
                    response.end(template.render(data.toString(), { messageList:results}))
                }
            })
            connection.end();

var delSql = `delete from message where id = ${query.id}`;
        var delSqlParams = [query.id]
        connection.query(delSql, delSqlParams, function (error, results, fields) {
            if (error) { console.log(error); }
            else {
                console.log(‘The solution is: ‘, results);
            }
        });