🗄️ Node.js – MySQL: CRUD Operations – Insert, Read, Update & Delete with Ease

🧲 Introduction – Why Learn CRUD with Node.js and MySQL?

CRUD operations are the foundation of all database-driven apps. Node.js, when paired with MySQL, allows developers to perform Create, Read, Update, and Delete actions on structured data—making it a go-to solution for RESTful APIs, admin panels, and CMS systems.

🎯 In this guide, you’ll learn:

• How to perform Insert, Select, Update, Delete operations
• How to use WHERE, ORDER BY, and LIMIT clauses
• Real SQL examples executed through Node.js

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📘 Topics Covered

🔹 Topic	📖 Description
➕ Node.js – MySQL Insert	Add new records to the MySQL table
🔍 Node.js – MySQL Select	Retrieve records using SELECT statements
🧾 Node.js – MySQL Where	Filter records with conditional logic
🔢 Node.js – MySQL Order By	Sort records based on one or more fields
♻️ Node.js – MySQL Update	Modify existing records based on conditions
❌ Node.js – MySQL Delete	Remove records using specific criteria
⛔ Node.js – MySQL Limit	Limit the number of rows returned by a SELECT query

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➕ Node.js – MySQL Insert Into

const db = require('./db');

const sql = `INSERT INTO employees (name, position, salary) VALUES ?`;
const values = [
  ['John Doe', 'Manager', 70000],
  ['Jane Smith', 'Developer', 55000]
];

db.query(sql, [values], (err, result) => {
  if (err) throw err;
  console.log("Records inserted: " + result.affectedRows);
});

🧪 Output:

Records inserted: 2

✅ Use parameterized queries (?) to prevent SQL injection.

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🔍 Node.js – MySQL Select From

db.query("SELECT * FROM employees", (err, results) => {
  if (err) throw err;
  console.log(results);
});

🧪 Output:

[
  { id: 1, name: "John Doe", position: "Manager", salary: 70000 },
  { id: 2, name: "Jane Smith", position: "Developer", salary: 55000 }
]

✅ Use aliases and specific fields when retrieving data in real apps.

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🧾 Node.js – MySQL WHERE Clause

db.query("SELECT * FROM employees WHERE position = 'Developer'", (err, results) => {
  if (err) throw err;
  console.log(results);
});

🧪 Output:

[
  { id: 2, name: "Jane Smith", position: "Developer", salary: 55000 }
]

✅ The WHERE clause filters rows based on conditions.

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🔢 Node.js – MySQL ORDER BY

db.query("SELECT * FROM employees ORDER BY salary DESC", (err, results) => {
  if (err) throw err;
  console.log(results);
});

🧪 Output:

Sorted by salary from highest to lowest

✅ Use ASC (ascending) or DESC (descending) to control sort order.

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♻️ Node.js – MySQL UPDATE

const sql = "UPDATE employees SET salary = ? WHERE name = ?";
db.query(sql, [60000, 'Jane Smith'], (err, result) => {
  if (err) throw err;
  console.log("Rows updated: " + result.affectedRows);
});

🧪 Output:

Rows updated: 1

✅ Always use conditions to avoid updating unintended rows.

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❌ Node.js – MySQL DELETE

db.query("DELETE FROM employees WHERE name = 'John Doe'", (err, result) => {
  if (err) throw err;
  console.log("Rows deleted: " + result.affectedRows);
});

🧪 Output:

Rows deleted: 1

✅ Add LIMIT 1 or use id to ensure precision and safety.

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⛔ Node.js – MySQL LIMIT

db.query("SELECT * FROM employees LIMIT 2", (err, results) => {
  if (err) throw err;
  console.log(results);
});

🧪 Output:

Returns only 2 records

✅ Useful for pagination or previewing rows.

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📌 Summary – Recap & Next Steps

CRUD operations are essential for working with relational data in Node.js. By combining MySQL’s powerful querying capabilities with Node’s asynchronous design, developers can build scalable data-driven apps.

🔍 Key Takeaways:

• Use INSERT INTO to add new data
• Retrieve records with SELECT and refine with WHERE, ORDER BY, and LIMIT
• Use UPDATE and DELETE carefully with conditionals
• Always sanitize inputs using prepared statements

⚙️ Real-World Uses:

• User registration and login systems
• Product inventory or order tracking
• Admin dashboards with update/delete access
• Paginated blog or comment systems

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❓ Frequently Asked Questions

❓ How do I prevent SQL injection in Node.js MySQL?
✅ Use placeholders (?) and parameter arrays in queries to automatically escape input.

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❓ What is the difference between SELECT * and SELECT column?
✅ SELECT * retrieves all columns, while SELECT column1, column2 retrieves specific fields—better for performance.

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❓ Can I use async/await with MySQL in Node.js?
✅ Use the mysql2 or promise-mysql library for Promise support with async/await syntax.

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❓ How do I paginate results from MySQL in Node.js?
✅ Combine LIMIT with OFFSET:

SELECT * FROM employees LIMIT 10 OFFSET 20

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