How to connect sql to javascript

In recent years, with the rapid development of front-end technology, more and more companies have begun to connect databases to JavaScript. This method allows users to easily manage and manipulate the database through the browser, so it is becoming increasingly popular. In this article, we will explain how to connect SQL to JavaScript.

First, you need to install the JavaScript runtime using Node.js, and install related modules using npm. Once the installation is complete, we can connect to the database using Node.js. Currently, the most popular module is the mysql module. You can install mysql using the following command:

npm install mysql

After the installation is complete, we can write JavaScript code to connect to the database. We first need to set the connection information of the database as follows:

var mysql = require('mysql');
var connection = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: 'password',
    database: 'example_db'
});

Next, we can connect to the database through the following code:

connection.connect(function(err) {
    if (err) {
        console.log('Error connecting to database:', err);
        return;
    }

    console.log('Connected to database!');
});

If the connection is successful, you will see "Connected to database!" output. Now we can execute SQL statements and get data from the database. Here is an example that retrieves data from the "users" table in our sample database:

connection.query('SELECT * FROM users', function(err, rows, fields) {
    if (err) {
        console.log('Error retrieving data:', err);
        return;
    }

    // 输出检索到的数据
    console.log(rows);
});

When we execute this code snippet, we will see the data from the "users" table on the console.

If you want to perform more advanced operations such as inserting, updating or deleting data, you can write the code like below:

connection.query('INSERT INTO users SET ?', { name: 'John', email: 'john@email.com' });

This code snippet will insert new user data into " users" table.

To summarize, connecting SQL to JavaScript is very simple. You just need to use Node.js and install the mysql module. You can then write JavaScript code to connect to the database, execute SQL, and add, delete, modify, and query the data. Hope this article helps you!

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