SQL Tutorial

Introduction to SQL

SQL (Structured Query Language) is the standard language used to communicate with relational databases. It allows you to create, read, update, and delete data efficiently, which is often referred to as CRUD operations.

📚 What Can SQL Do?

• Retrieve data from a database
• Insert new records into a table
• Update existing records
• Delete records
• Create and manage database tables
• Set permissions on tables, procedures, and views

🔠 Basic SQL Syntax

A basic SQL query looks like this:

SELECT column1, column2 FROM table_name WHERE condition;
  

Let’s break it down:

• SELECT – Specifies the columns to retrieve
• FROM – Specifies the table to query
• WHERE – Filters records based on conditions

🧪 Live-Like Example

Imagine we have a table called students:

+----+----------+--------+
| id | name     | grade  |
+----+----------+--------+
| 1  | John     | A      |
| 2  | Priya    | B      |
| 3  | Michael  | A      |
+----+----------+--------+
  

To select all students with grade 'A', you would write:

SELECT * FROM students WHERE grade = 'A';
  

📌 Common SQL Commands

• SELECT – Get data
• INSERT INTO – Add new data
• UPDATE – Modify existing data
• DELETE – Remove data
• CREATE TABLE – Make a new table
• DROP TABLE – Delete a table completely

🔍 SQL is Case-Insensitive

SQL keywords like SELECT, FROM, and WHERE are not case-sensitive. However, it’s a good practice to write them in uppercase for clarity.