What are DDL, DML, and DCL?

• DDL (Data Definition Language) - Data Definition Language. Used for creating, modifying, and deleting the structure of a database.
• DML (Data Manipulation Language) - Data Manipulation Language. Used for inserting, updating, deleting, and retrieving data from a database.
• DCL (Data Control Language) - Data Control Language. Used for defining access rights and permissions for database users.

Examples:

• DDL:

  -- Creating a table
  CREATE TABLE customers (
      id INT PRIMARY KEY,
      name VARCHAR(255)
  );
  
  -- Modifying a table
  ALTER TABLE customers ADD COLUMN email VARCHAR(255);
  
  -- Dropping a table
  DROP TABLE customers;
  

• DML:

  -- Inserting data
  INSERT INTO customers (id, name) VALUES (1, 'John Doe');
  
  -- Updating data
  UPDATE customers SET name = 'Jane Doe' WHERE id = 1;
  
  -- Deleting data
  DELETE FROM customers WHERE id = 1;
  
  -- Selecting data
  SELECT * FROM customers;
  

• DCL:

  -- Granting permissions
  GRANT SELECT, UPDATE ON customers TO user1;
  
  -- Revoking permissions
  REVOKE UPDATE ON customers FROM user1;