To connect MySQL data to Node.js application, 1. Install the mysql2 module; 2. Create a connection configuration, including host, user, password, database, etc.; 3. Establish a connection and handle errors; 4. Execute SQL queries and process results; 5. Close the connection or use the connection pool to manage the connection; Common problems include network blockage, insufficient account permissions, firewall restrictions, password errors and SSL connection problems. Follow the steps to troubleshoot.
Connecting MySQL database to Node.js application is not complicated, but some details are prone to errors. As long as you are prepared for dependencies and configured correctly, you can basically connect smoothly.
The following is a few common steps and points to pay attention to how to do it.
Install the MySQL module
Node.js itself does not have built-in MySQL support, you need to install a MySQL client module first. The most commonly used is mysql or mysql2 , which has better performance and also supports Promise.
Run command to install:
npm install mysql2
If you don't want to change modules, it's OK to continue using mysql , but it is recommended to use mysql2 , which has good compatibility.
Create a connection configuration
Before connecting to the database, you need to prepare the connection information. Including host name, user name, password, database name, and optional port.
Usually you will write a configuration object, such as this:
const mysql = require('mysql2');
const connection = mysql.createConnection({
host: 'localhost',
user: 'your_username',
password: 'your_password',
database: 'your_database'
});These parameters must be filled in according to your actual database environment. For example, if the database is not local, the host must be changed to the corresponding IP or domain name.
Establish a connection and execute a query
After creating the configuration, you can establish a connection:
connection.connect((err) => {
if (err) {
console.error('Connection failed:', err.stack);
return;
}
console.log('Connection is successful, ID is:', connection.threadId);
});After the connection is successful, you can execute SQL query:
connection.query('SELECT 1 1 AS solution', (error, results, fields) => {
if (error) throw error;
console.log('Query result:', results[0].solution);
});Don't forget to close the connection at the end:
connection.end();
Or if you want to control the connection life cycle more flexibly, you can use a connection pool, which is suitable for applications with many concurrent requests.
Frequently Asked Questions
- Network blockage : The remote database needs to confirm whether the current IP connection is allowed.
- Insufficient account permissions : Whether MySQL users have permission to access the corresponding database.
- Firewall restrictions : Port 3306 may be open on cloud servers.
- Password error or user does not exist : Check whether the username and password are accurate.
- SSL connection issues : Some managed databases require SSL to be mandated, and you can add
ssl: 'Amazon RDS'or other modes to the configuration.
If you report an error ER_ACCESS_DENIED_ERROR when connecting, it is likely that the user name or password is wrong; if it is ECONNREFUSED , it may be that the database is not running or the port is not running.
Basically that's it. Follow these steps to connect to MySQL in most cases.
The above is the detailed content of how to connect to mysql from node.js. For more information, please follow other related articles on the PHP Chinese website!
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