SQL (Structured Query Language)

What is SQL?

SQL(Structured Query Language) is a database language used to store, retrieve, update, and manage data in a relational database.

Why Use SQL?

• Store large amounts of data

• Retrieve data quickly

• Update existing records

• Delete unwanted records

• Generate reports and analysis

• Manage relational databases

Benefits of SQL

• Easy to learn

• Fast data retrieval

• Supports large datasets

• Used in many industries

• Works with databases like MySQL, PostgreSQL, SQL Server, and Oracle

SQL Syntax

• SQL syntax refers to the set of rules used to write SQL statements correctly.

Basic Syntax

SELECT column_name
FROM table_name;

SQL Keywords:

• SELECT - Retrieve data

• FROM - Specify the table

• WHERE - Filter records

• INSERT - Add new records

• UPDATE - Modify existing records

• DELETE - Remove records

• CREATE - Create a database or table

• ALTER - Modify a table

• DROP - Delete a database or table

• ORDER BY - Sort data

• GROUP BY - Group records

• HAVING - Filter grouped data

SQL Data Types

• SQL data types define the type of data that can be stored in a table column.

• INT - Stores whole numbers - 101

• VARCHAR(n) - Stores text up to a specified length - 'database'

• CHAR(n) - Stores fixed-length text - 'A'

• DECIMAL(p,s) - Stores decimal numbers - 10.00

• DATE - Stores dates - 29-07-2026

• TIME - Stores time - 10:30:00

• TIMESTAMP - Stores data and time - 2026-07-29 10:30:00

• BOOLEAN - Stores TRUE or FALSE - TRUE