CODE EXAMPLE FOR JAVASCRIPT

crud in node

# Config DB and query function 

const mysql = require('mysql');
const mysqlConnection = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: 'QAZwsx@123',
    database: 'blog',
    multipleStatements: true
});

mysqlConnection.connect((err) => {
    if (!err) {
        console.log('DB Connection Established Successfully');
        return true;
    } else {
        console.log('Connection Failed!' + JSON.stringify(err, undefined, 2));
        return false;
    }
});

class DB {
    constructor() {
        this.connection = mysqlConnection;
    }
    // All categories
    getCategories() {
        return new Promise((resolve, reject) => {
            this.connection.query('SELECT * FROM categories', (err, rows) => {
                if (!err)
                    resolve(rows);
                else
                    reject(err);
            });
        });
    }
    // Get category by id
    getCategoryById(id) {
        return new Promise((resolve, reject) => {
            this.connection.query('SELECT * FROM categories WHERE id = ?', [id], (err, rows) => {
                if (!err)
                    resolve(rows);
                else
                    reject(err);
            });
        });
    }
    // Add category
    addCategory(category) {
        return new Promise((resolve, reject) => {
            this.connection.query('INSERT INTO categories SET ?', [category], (err, rows) => {
                if (!err)
                    resolve(this.getCategories());
                else
                    reject(err);
            });
        });
    }
    // Update category
    updateCategory(id, category) {
        return new Promise((resolve, reject) => {
            this.connection.query('UPDATE categories SET ? WHERE id = ?', [category, id], (err, rows) => {
                if (!err)
                    resolve(this.getCategories());
                else
                    reject(err);
            });
        });
    }
    // Delete category
    deleteCategory(id) {
        return new Promise((resolve, reject) => {
            this.connection.query('DELETE FROM categories WHERE id = ?', [id], (err, rows) => {
                if (!err)
                    resolve(this.getCategories());
                else
                    reject(err);
            });
        });
    }
}
module.exports = DB;