SQL Introduction

Types of SQL commands

• DDL - Data Definition Language

  DDL is used to define and manage the structure of a database and its objects.
  CREATE, DROP, ALTER, TRUNCATE , COMMENT , RENAME

• DML - Data Manipulation Language

  DML is concerned with modifying and manipulating data stored in a database.
  INSERT, UPDATE, DELETE

• DQL - Data Query Language

  DQL is specifically designed for querying and retrieving information from databases.
  SELECT

• DCL - Data Control Language

  DCL includes commands that are responsible for granting or revoking permissions, privileges, and roles to users and roles, thus ensuring data security and access control
  GRANT , REVOKE

• TCL - Transaction Control Language

  TCL is used for managing transactions within a database. A transaction is a sequence of one or more database operations (such as data manipulation or data definition) that are executed as a single unit of work.
  COMMIT, ROLLBACK, SAVEPOINT, SET TRANSACTION

DQL - Data Query Language

What is SQL

CREATE TABLE student ( id int(2) NOT NULL auto_increment,  name varchar(50) NOT NULL default '', 
class varchar(10) NOT NULL default '', mark int(3) NOT NULL default '0', 
UNIQUE KEY id (id) ) TYPE=MyISAM;

Adding records

INSERT INTO student VALUES (1, 'John Deo', 'Four', 75);
INSERT INTO student VALUES (2, 'Max Ruin', 'Three', 85);
INSERT INTO student VALUES (3, 'Arnold', 'Three', 55);
INSERT INTO student VALUES (4, 'Krish Star', 'Four', 60);
INSERT INTO student VALUES (5, 'John Mike', 'Four', 60);
INSERT INTO student VALUES (6, 'Alex John', 'Five', 55);