Revisiting Basics of SQL

Before starting up on learning first let's learn what is SQL.

SQL, or Structured Query Language, is a programming language designed for managing and manipulating relational database management systems (RDBMS) and, in some cases, for manipulating and querying data in non-relational databases. SQL provides a standardized way to interact with databases, allowing users to define, manipulate, and query data.

- Table Structure:
— Data in a Relational Database Management System (RDBMS) is stored in tables.
— A table is a collection of related entries, organized in columns and rows.

- Fields in a Table:
— Fields are smaller entities within a table, corresponding to columns.
— Each field stores specific information about entries in the table.

- Records:
— A record is an individual entry in a table.
— Records are horizontal entities in a table, capturing detailed information about specific entities.

• Database Composition:
  — A database typically contains one or more tables.
  — Each table has a unique name, contributing to the organization and storage of data in the RDBMS.

Types of commands in SQL:

1. DDL (Data Definition Language): SQL includes commands for defining and modifying the structure of database objects, such as tables, indexes, and constraints. Examples include CREATE TABLE, ALTER TABLE, and DROP TABLE.
2. DML (Data Manipulation Language): SQL includes commands for interacting with data stored in the database. This includes querying data, inserting new records, updating existing records, and deleting records. Examples include SELECT, INSERT, UPDATE, and DELETE.
3. DCL (Data Control Language): SQL includes commands for controlling access to data in the database. This involves granting or revoking privileges to users. Examples include GRANT and REVOKE.
4. TCL(Transaction Control Language): Transaction Control Language, is a subset of SQL (Structured Query Language) that deals with managing transactions within a database. The purpose of TCL commands is to control the transactions to ensure the integrity and consistency of the data within a database. Examples include COMMIT and ROLLBACK .