SQL Guide

1. What is SQL?

SQL (Structured Query Language) is used to store, retrieve, and manage data in databases.

CREATE TABLE students (
  id INT,
  name VARCHAR(50),
  marks INT
);

INSERT INTO students VALUES (1, 'John', 80);

SELECT * FROM students;

SELECT * FROM students WHERE marks > 50;

UPDATE students SET marks = 90 WHERE id = 1;

DELETE FROM students WHERE id = 1;

SELECT * FROM A
JOIN B ON A.id = B.id;

SELECT AVG(marks), MAX(marks) FROM students;