ToolScope Notes
SQL Notes in Simple English — Code Scope
Free SQL notes for beginners: what a database is, tables, rows and columns, creating tables and data types, the full CRUD set, WHERE, ORDER BY and LIMIT, JOINs, keys and database design, constraints, subqueries, indexes, transactions, views and permissions — and a complete store (dukaan) database project. Real SQL queries with real result tables, common mistakes and practice tasks in every lesson. From the Code Scope SQL series.
SQL Notes
12 LESSONS · CODE SCOPE SERIES DB.1–DB.12The language databases listen to: what a database is, tables, rows and columns, CREATE TABLE and data types, the full CRUD set, WHERE with ORDER BY and LIMIT, JOINs across tables, primary and foreign keys, constraints, subqueries, indexes, transactions, views and permissions — and one complete project, a store (dukaan) database.
Database Kya Hai? + SQL Ka Taaruf
What a database is and why apps need one: tables, rows and columns, your first SELECT — and the SQL vs NoSQL comparison, with when each one wins.
Pehli Table Banana — CREATE + Data Types
Build your first table: CREATE TABLE, the main data types (INT, VARCHAR, DECIMAL, DATE, BOOLEAN), and reading the DESCRIBE result.
CRUD — INSERT / SELECT / UPDATE / DELETE
The four jobs every app does with data: add rows with INSERT, read with SELECT, change with UPDATE, remove with DELETE — and the WHERE that keeps them safe.
WHERE, ORDER BY, LIMIT — Chhanna Aur Tartib
Filter and arrange your answers: WHERE with AND/OR, LIKE, IN and BETWEEN, sorting with ORDER BY, and top results with LIMIT.
JOINs — Do Tables Ko Jorna
Answer questions that live in two tables: INNER JOIN for matching rows only, LEFT JOIN for everyone — and the NULL that tells the truth.
Primary Key, Foreign Key + Design Ke Usool
Give every row an identity and every table a safe link: PRIMARY KEY, FOREIGN KEY, the errors that guard them, and three design rules.
Constraints Deep — Database Ke Sakht Usool
Stop bad data at the door: NOT NULL, UNIQUE, DEFAULT, CHECK, and what happens to children when a parent row is deleted.
Subqueries — Sawal Ke Andar Sawal
A question inside a question: subqueries in WHERE, in the SELECT list, and with IN — above-average students without knowing the average.
Indexes — Database Ki Firasat (Speed Ka Raaz)
Why big tables answer slowly and how an index fixes it: CREATE INDEX, reading EXPLAIN, and the honest cost every index charges.
Transactions — Ya Sab, Ya Kuch NAHI
All or nothing: the bank-transfer disaster, BEGIN / COMMIT / ROLLBACK, and how a transaction makes a half-done job impossible.
Views + Data Ko Mehfooz Rakhna (Users & Permissions)
Saved questions and safe doors: CREATE VIEW, why a view is live and not a photo, and GRANT — giving each user only the access they need.
SQL Project: Dukaan (Store) Ka Mukammal Database
The whole series in one project: a store's products, customers, orders and order items — schema, data, sales reports and stock alerts.