Basic SQL Commands

Introduction to CRUD

SQL commands are categorized into four main operations, often referred to as CRUD:

• Create - Adding new data (CREATE and INSERT).
• Read - Retrieving data (SELECT).
• Update - Modifying existing data (UPDATE).
• Delete - Removing data (DELETE).

1. CREATE Command

The CREATE command is used to create new tables in a SQL database. Here’s an example:

CREATE TABLE users (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(100),
  email VARCHAR(100)
);

This command creates a `users` table with three columns: `id`, `name`, and `email`.

2. INSERT Command

The INSERT command is used to add new data to a table. Example:

INSERT INTO users (name, email) 
VALUES ('Jane Doe', 'jane@example.com');

This command inserts a new user record into the `users` table.

3. SELECT Command

The SELECT command is used to retrieve data from one or more tables. Example:

SELECT * FROM users;

This command retrieves all the records from the `users` table.

4. UPDATE Command

The UPDATE command is used to modify existing records in a table. Example:

UPDATE users 
SET email = 'newemail@example.com' 
WHERE id = 1;

This command updates the email of the user with an `id` of 1.

5. DELETE Command

The DELETE command is used to remove records from a table. Example:

DELETE FROM users 
WHERE id = 1;

This command deletes the user with an `id` of 1 from the `users` table.