Syntax

Database Operations

• Create a database:

CREATE DATABASE $DB_NAME;

• Use a database:

USE $DB_NAME;

• Drop a database:

DROP DATABASE $DB_NAME;

Table Operations

• Create a table:

CREATE TABLE $TABEL_NAME (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(100),
  email VARCHAR(255)
);

• Alter a table:

ALTER TABLE $TABEL_NAME ADD age INT;

• Drop a table:

DROP TABLE $TABEL_NAME;

Data Manipulation (CRUD)

• Create:

INSERT INTO $TABEL_NAME (name, email) VALUES ('John', '[e-mail]');

• Read:

SELECT * FROM $TABEL_NAME;
SELECT name FROM users WHERE id = 1;

• Update:

UPDATE $TABEL_NAME SET email = '[e-mail]' WHERE id = 1;

• Delete:

DELETE FROM $TABEL_NAME WHERE id = 1;

Constraints

Type	Description
PRIMARY KEY	Unique identifier for each row
FOREIGN KEY	Links a column to a column in another table
UNIQUE	Ensures all values in a column are different
NOT NULL	Column must have a value
CHECK	Validates data based on a condition
DEFAULT	Sets default value for a column

Example

CREATE TABLE orders (
  id INT PRIMARY KEY,
  user_id INT,
  amount DECIMAL(10, 2) DEFAULT 0.00,
  CONSTRAINT fk_user FOREIGN KEY (user_id) REFERENCES users(id)
);