Node.js MySQL Delete Query

We use SQL DELETE Query to delete data with some condition from MySQL Table.

Syntax:

• This will delete all rows of customers’ tables but everything else will remain as it is (indexing, etc).

  DELETE FROM users

• This will delete all rows of users table where userId is 2.

  DELETE FROM users WHERE userId = 2

Modules:

• mysql: To handle sql connection and queries

  npm install mysql

SQL users table preview:

Example 1: Delete all rows from users table

Javascript

const mysql = require("mysql");

let db_con  = mysql.createConnection({
    host: "localhost",
    user: "root",
    password: '',
    database: 'gfg_db'
});

db_con.connect((err) => {
    if (err) {
      console.log("Database Connection Failed !!!", err);
      return;
    }

    console.log("We are connected to gfg_db database");

    // here is our query
    let query = 'DELETE FROM users';

    db_con.query(query, (err, rows) => {
        if(err) throw err;

        console.log('Cleared users Table');
    });
});

Output:

Example 2: Delete all users whose name = ‘pratik’.

• Approach 1: Hard code the value

Javascript

const mysql = require("mysql");

let db_con  = mysql.createConnection({
    host: "localhost",
    user: "root",
    password: '',
    database: 'gfg_db'
});

db_con.connect((err) => {
    if (err) {
      console.log("Database Connection Failed !!!", err);
      return;
    }

    console.log("We are connected to gfg_db database");

    // This is our Hard Coded Query
    let query = "DELETE FROM users WHERE name = 'pratik'";

    db_con.query(query, (err, rows) => {
        if(err) throw err;

        console.log('Number of rows deleted = ' + rows.affectedRows);
    });
});

• Approach 2: Dynamic Query

Javascript

const mysql = require("mysql");

let db_con  = mysql.createConnection({
    host: "localhost",
    user: "root",
    password: '',
    database: 'gfg_db'
});

db_con.connect((err) => {
    if (err) {
      console.log("Database Connection Failed !!!", err);
      return;
    }

    console.log("We are connected to gfg_db database");

    // notice the ? in below query
    let query = "DELETE FROM users WHERE name = ?";

    // Dynamic Value
    let name = 'pratik';

    // Notice the name variable below
    // It will replace the ? in query
    db_con.query(query, name, (err, rows) => {
        if(err) throw err;

        console.log('Number of rows deleted = ' + rows.affectedRows);
    });
});

Output: