Node.js study notes (10)#Database operation

Table of contents

1. Install the mysql module

2. Import and configure mysql

3. Database crud operation

1. Insert operation

2. Query operation

3.Update operation

4. Delete operation

①Physical deletion

②Logical deletion (recommended)

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1. Install the mysql module

npm i mysql

2. Import and configure mysql

const mysql = require('mysql')
const db = mysql.createPool({
  host:'127.0.0.1', //数据库ip地址
  user:'root',      //数据库账号
  password:'123456',//数据库密码
  database:'test_01'//数据库名称  
})

db.getConnection(function (err, connection) {
  if (err) {
    throw new Error(err.message);
  } else {
    console.log("建立连接成功");
    console.log(db._allConnections.length); //  1
    connection.query("select 1", function (err, results) {
      if(err) throw new Error(err.message) //失败返回错误信息
      console.log(results) // 成功返回[ RowDataPacket { '1': 1 } ]
      connection.destory(); // 当一个连接不再需要使用且需要从连接池中移除时，用connection对象的destroy方法
      console.log(db._allConnections.length); // 0
    });
  }
  db.end(); // 当一个连接池不再需要使用时，用连接池对象的end方法关闭连接池
});

Configuration parameters:

host	Host address (default: localhost)
user	username
password	password
port	Port number (default: 3306)
database	Database name
charset	Connection character set (default: 'UTF8_GENERAL_CI', note that the letters in the character set must be uppercase)
localAddress	This IP is used for TCP connections (optional)
socketPath	Path to connect to unix domain, ignored when using host and port
timezone	Time zone (default: 'local')
connectTimeout	Connection timeout (default: no limit; unit: milliseconds)
stringifyObjects	Whether to serialize the object
typeCast	Whether to convert column values ​​into local JavaScript type values ​​(default: true)
queryFormat	Custom query statement formatting method
supportBigNumbers	When the database supports bigint or decimal type columns, this option needs to be set to true (default: false)
bigNumberStrings	supportBigNumbers and bigNumberStrings enable forcing bigint or decimal columns to be returned as JavaScript string types (default: false)
dateStrings	Force timestamp, datetime, and data types to be returned as string types instead of JavaScript Date types (default: false)
debug	Enable debugging (default: false)
multipleStatements	Whether to allow multiple MySQL statements in one query (default: false)
flags	Used to modify the connection flag
ssl	Use the ssl parameter (in the same format as the crypto.createCredenitals parameter) or a string containing the name of the ssl profile. Currently only Amazon RDS profiles are bundled.

3. Database crud operation

1. Insert operation

const param = { name: "zhangsan", gender: "男", age: "20" };
const sqlStr = "insert into user (name,gender,age) values (?,?,?)";
db.query(sqlStr, [param.name, param.gender, param.age], (err, res) => {
  if (err) throw new Error(err.message);
  if (res.affectedRows == 1) {
    console.log("插入成功");
  }
});

2. Query operation

const param = {name:"zhangsan"}
const sqlStr = "select * from user where name = ?";
db.query(sqlStr, [param.name], (err, res) => {
    if (err) throw new Error(err.message);
    if (res) {
      console.log(res);
      //[ RowDataPacket { id: 1, name: 'zhangsan', gender: '男', age: '20' } ]
    }
});

3.Update operation

const param = { name: "lisi", age: "23", id: 1 };
const sqlStr = "update user set name = ?,age = ? where id = ?";
db.query(sqlStr, [param.name, param.age, param.id], (err, res) => {
  if (err) throw new Error(err.message);
  if (res.affectedRows == 1) {
    console.log("更新成功");
  }
});

4. Delete operation

①Physical deletion

const param = { id: 1 };
const delSql = 'delete from user where id = ?';
db.query(delSql, [param.id], (err, res) => {
  if (err) throw new Error(err.message);
  if (res.affectedRows == 1) {
    console.log("删除成功");
  }
});

②Logical deletion (recommended)

const param = { status: 0 ,id: 1 };
const delSql = 'update user set status = ? where id = ?';
db.query(delSql, [param.status,param.id], (err, res) => {
  if (err) throw new Error(err.message);
  if (res.affectedRows == 1) {
    console.log("删除成功");
  }
});