SQL Commands

1. Data Definition Language (DDL)

• Create

  CREATE TABLE Students (
      StudentID int,
      Name varchar(255),
      Age int
  );
  
  

• Alter

  ALTER TABLE Students
  ADD COLUMN Grade int;
  

  • The ALTER TABLE statement is used to add, delete, or modify columns in an existing table.
  • The ALTER TABLE statement is also used to add and drop various constraints on an existing table.

• Drop

DROP TABLE Students;

• Truncate

  TRUNCATE TABLE Students;
  
  

• Rename

  RENAME TABLE Students TO Pupils;
  
  

2. Data Manipulation Language (DML)

• Select

  SELECT * FROM Students;
  
  

• Insert

  INSERT INTO Students (StudentID, Name, Age)
  VALUES (1, 'John Doe', 20);
  
  

• Update

  UPDATE Students
  SET Age = 21
  WHERE StudentID = 1;
  
  

• Delete

  DELETE FROM Students
  WHERE StudentID = 1;
  
  

3. Data Control Language (DCL)

• Grant

  GRANT SELECT ON Students TO User1;
  
  

• Revoke

  REVOKE SELECT ON Students FROM User1;
  
  

4. Transaction Control Language (TCL)

• Commit

  COMMIT;
  
  

• Rollback

  ROLLBACK;
  
  

• Savepoint

  SAVEPOINT Savepoint1;