I have a question, Before I change my code, I got error [error: connection lost: the server closed the connection.], possibly because its idle for sometime.
This is my old code.
const dbConn = mysql.createConnection({
host : 'localhost',
user : 'root',
password : '',
database : 'test'
});
dbConn.connect(function(err) {
if(err) throw err;
console.log("Database Connected!");
})
module.exports = dbConn;
After searching for a while, most of it recommend using createPool intead of createConnection, so I change my code to this
const dbConn = mysql.createPool({
host : 'localhost',
user : 'root',
password : '',
database : 'test'
});
module.exports = dbConn;
Then my question is, do I have to release the connection everytime we complete a query? This is how I do query.
dbConn.query("SELECT * FROM spesialisasi s ORDER BY s.nama_spesialisasi ASC ",
function(err, res) {
if(err) {
console.log("error: ", err);
result(err, null);
} else {
result(null, res);
}
}
)
From my knowledge, pool.query() will automatically release the connection when the query completes. Here's the section on connection pooling from the MySQL NPM docs
Related
Hello Everyone,
I'm a beginner in Node.js Mysql. I have connected to Node.js with mysql. While starting the Node.js server, I got the error like " code: 'ER_TOO_MANY_USER_CONNECTIONS', " further I will attach the mysql db connection code below. Any type of help would be appreciated. Thanks in advance...
var db = mysql.createPool({
host: 'xxxxxxxxxxxxxxxxx',
port: 'xxx',
user: 'xxxx',
password: 'xxx',
database: 'xxx'
});
db.getConnection((err, tempConn) => {
if (err) {
console.log(err);
}
else {
tempConn.release();
console.log('Mysql Connected');
}
});
module.exports={db};
If you're creating a pool you don't need to use getConnection. There is a shortcut that allows you to use it directly. If you do use getConnection you must follow it with a query, then you may release the connection. Your example is missing a query.
Here is a helpful template for using a pool config:
// in your application initialization file such as app.js
//
// other require items here as well like express maybe?
//
const mysql = require('mysql');
const connection = mysql.createPool({
connectionLimit: 10,
host: process.env.DB_HOST || '127.0.0.1',
user: process.env.DB_USER || 'local_user',
password: process.env.DB_PASSWORD || 'local_password',
database: process.env.DB_NAME || 'local_database',
multipleStatements: true,
charset: 'utf8mb4' // necessary if you might need support for emoji characters
});
connection.on('connection', function (connection) {
// handy for testing
console.log('Pool id %d connected', connection.threadId);
});
connection.on('enqueue', function () {
// handy for testing
console.log('Waiting for available connection slot');
});
global.db = connection;
//
// other app setup stuff here like app.set, app.engine, app.use, module.exports = app and all that good stuff
//
// later…
// everywhere else in your app, use the global db variable when running queries
// ../new_users.js or similar maybe?
const _create_user = (user_payload) => {
db.query(
'INSERT INTO users SET ?', user_payload, function(error, results, fields) {
if (error) throw error;
console.log(results);
});
}
// maybe we are in a module that has access to
// the request object so we can use something
// that has come via POST
//
// here is a manual object as a placeholder…
let new_user = {
first_name: 'John',
last_name: 'Smith',
email: 'j.smith#example.com',
password: 'keyboard_cat'
}
_create_user(new_user);
I make a connection to mysql using node js,
connection is successful, event if i put a wrong port,
but query didn't return any results.
mysql version for node js is : "mysql": "^2.18.1"
data base version : 5.5.47
(port : number or string : same result)
var express = require('express');
var mysql = require('mysql');
var app = express();
//
var connection = mysql.createConnection({
host: 'localhost',
database: 'mydb',
user : 'root',
password: 'pwd',
port : '3306'
});
connection.connect(function(error){
if(!error){
console.log(error)
} else{
console.log('Connected')
}
});
connection.query("SELECT * FROM members", function(error, rows){
if(!error){
console.log("Error in the query")
console.log(error)
}else{
console.log("successfull")
console.log(rows)
}
})
app.listen(4000)
Following logic is incorrect. it says if not error then log error so you will never get your rows.
if(!error){
console.log("Error in the query")
console.log(error)
}else{
console.log("successfull")
console.log(rows)
}
Remove the !
// So I am using mysql with node and express framework and the first time I created a test example everything worked fine. But then I tried to create a second project and now the routing seems to not being read.
And the respond back I get is:
[nodemon] restarting due to changes...
[nodemon] starting `node app.js`
Server started on port 8000
mysql connected...
//I am also supposed to get the result back:
OkPackege{...
...
...
...
}
//But I am not getting it. Any Ideas...? thanks.
The scrips that i have are as follow:
const express = require('express');
const mysql = require('mysql');
const db = mysql.createConnection({
host : 'localhost',
user : 'root',
password : 'LEoking1987'
//database : 'nodesql'
});
db.connect((err) => {
if(err){
throw err;
}
console.log('mysql connected...');
});
const app = express();
// Creates satabase if it does not exist yet.
app.get('/createdb',(req,res) => {
let sql = 'CREATE DATABASE nodesql';
db.query(sql, (err, result) => {
if(err) throw err;
console.log(result);
res.send('Database created...');
});
});
app.listen('8000',()=>{
console.log('Server started on port 8000');
});
add debug: true in your mysql connection params like
mysql.createConnection({
host: 'localhost',
user: 'root',
password: 'LEoking1987'
database: 'nodesql'
debug: true,
})
I am able to create a MySQL connection like this:
var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'localhost',
user : 'me',
password : 'secret',
database : 'my_db'
});
connection.connect();
But I would rather like to initiate a pool and use it across my project.
Just to help some one in future, this worked for me:
I created a mysql connector file containing the pool:
// Load module
var mysql = require('mysql');
// Initialize pool
var pool = mysql.createPool({
connectionLimit : 10,
host : '127.0.0.1',
user : 'root',
password : 'root',
database : 'db_name',
debug : false
});
module.exports = pool;
Later you can simply include the connector in another file lets call it manageDB.js:
var pool = require('./mysqlConnector');
And made a callable method like this:
exports.executeQuery=function(query,callback){
pool.getConnection(function(err,connection){
if (err) {
connection.release();
throw err;
}
connection.query(query,function(err,rows){
connection.release();
if(!err) {
callback(null, {rows: rows});
}
});
connection.on('error', function(err) {
throw err;
return;
});
});
}
You can create a connection file, Let's called dbcon.js
var mysql = require('mysql');
// connect to the db
dbConnectionInfo = {
host: "localhost",
port: "3306",
user: "root",
password: "root",
connectionLimit: 5, //mysql connection pool length
database: "db_name"
};
//For mysql single connection
/* var dbconnection = mysql.createConnection(
dbConnectionInfo
);
dbconnection.connect(function (err) {
if (!err) {
console.log("Database is connected ... nn");
} else {
console.log("Error connecting database ... nn");
}
});
*/
//create mysql connection pool
var dbconnection = mysql.createPool(
dbConnectionInfo
);
// Attempt to catch disconnects
dbconnection.on('connection', function (connection) {
console.log('DB Connection established');
connection.on('error', function (err) {
console.error(new Date(), 'MySQL error', err.code);
});
connection.on('close', function (err) {
console.error(new Date(), 'MySQL close', err);
});
});
module.exports = dbconnection;
Now include this connection to another file
var dbconnection = require('../dbcon');
dbconnection.query(query, params, function (error, results, fields) {
//Do your stuff
});
There is some bugs in Utkarsh Kaushik solution:
if (err), the connection can not be released.
connection.release();
and when it has an err, next statement .query always execute although it gets an error and cause the app crashed.
when the result is null although query success, we need to check if the result is null in this case.
This solution worked well in my case:
exports.getPosts=function(callback){
pool.getConnection(function(err,connection){
if (err) {
callback(true);
return;
}
connection.query(query,function(err,results){
connection.release();
if(!err) {
callback(false, {rows: results});
}
// check null for results here
});
connection.on('error', function(err) {
callback(true);
return;
});
});
};
You do also can access the Mysql in a similar way by firstly importing the package by entering npm install mysql in the terminal and installing it & initialize it.
const {createPool} = require("mysql");
const pool = createPool({
host : 'localhost',
user : 'me',
password : 'secret',
database : 'my_db'
)};
module.exports = pool;
I'm getting error :
error:Error: Handshake inactivity timeout
I connected mysql to node by like this.
Install mysql
npm install mysql
var mysql = require('mysql');
let connection = mysql.createConnection({
host: 'localhost',
user: 'root',
port: '8888', /* port on which phpmyadmin run */
password: 'root',
database: 'dbname',
socketPath: '/Applications/MAMP/tmp/mysql/mysql.sock' //for mac and linux
});
connection.connect(function(err) {
if (err) {
return console.error('error: ' + err.message);
}
console.log('Connected to the MySQL server.');
});
You can use node-mysql, It very easy to use. I have used once, Here is the example :-
var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'localhost',
user : 'me',
password : 'secret',
database : 'my_db'
});
connection.connect();
connection.query('SELECT 1 + 1 AS solution', function(err, rows, fields) {
if (err) throw err;
console.log('The solution is: ', rows[0].solution);
});
connection.end();
Use Connection Pool:
var mysql = require('mysql');
var pool = mysql.createPool({
host : 'example.org',
user : 'bob',
password : 'secret'
});
pool.getConnection(function(err, connection) {
// Use the connection
connection.query( 'SELECT something FROM sometable', function(err, rows) {
// And done with the connection.
connection.release();
// Don't use the connection here, it has been returned to the pool.
});
});