Introduction to SQL

What is a Database?

Database is an electronic place/system where data is stored in a way that it can be easily accessed, managed, and updated.

What is DBMS?

A database management system (DBMS) is a software system for creating and managing databases. A DBMS enables end users to create, protect, read, update and delete data in a database.

What is RDBMS?

• RDBMS (Relational Database Management System) is a DBMS based on the concept of tables (also called relations).
• Data is organized into tables (also known as relations) with rows (records) and columns (attributes).
• Eg - MySQL, PostgreSQL, Oracle etc.

Types of Databases

Relational Database

A relational database stores data in a table composed of rows and columns. The table represents an object or entity, such as users, customers, orders, etc.

Non-Relational database

Non-relational databases different from relational databases because they do not store data in tabular form.

What is SQL?

SQL is Structured Query Language used to store, manipulate and retrieve data from RDBMS.

Note
1. It is not a database, it is a language used to interact with database.
2. SQL keywords are NOT case sensitive. Eg:- select is the same as SELECT in SQL.

We use SQL for CRUD Operations :-
1. CREATE - To create databases, tables etc...
2. READ - To read data present in the database.
3. UPDATE - Modify already inserted data.
4. DELETE - Delete database, table or specific data point/tuple/row or multiple rows.

SQL v/s MySQL

SQL is a language used to perform CRUD operations in Relational DB, while MySQL is a RDBMS that uses SQL.