CODEBHAVYA β€’ DATABASE SYSTEMS

Understand Databases. Write SQL with Confidence.

Learn how data is designed, related, queried, protected and recoveredβ€”from the first table to interview-grade SQL and real database projects.

Start Level 1 β†’ Explore 18-Level Roadmap
18Structured levels
4Learning stages
10Skill actions
3Capstone projects
UNIVERSITY DATABASEPK β†’ FK

students

PK student_id

name

department

enrolments

FK student_id

FK course_id

grade

courses

PK course_id

title

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SELECT s.name, c.title, e.grade
FROM students s
JOIN enrolments e ON e.student_id = s.student_id
JOIN courses c ON c.course_id = e.course_id;
YOUR COURSE CHECKPOINTS

Build Momentum Across All 18 Levels

Use the roadmap as your study checklist. Progress is saved only in this browser and does not require sign-in.

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THE LEARNING SYSTEM

Ten Actions in Every Complete Lesson

Reading alone is not mastery. Each level is designed to move from a clear mental model to independent problem solving.

01Understand
02Visualize
03Trace
04Apply
05Predict
06Execute
07Debug
08Practise
09Explain
10Master
COMPLETE COURSE ARCHITECTURE

Four Stages from Foundations to Placement

Follow the stages in sequence. Every later skill rests on a database idea introduced earlier.

PART 1 β€’ LEVELS 1–501

Model the Data

Understand database purpose, architectures, ER diagrams, relations and algebra.

PART 2 β€’ LEVELS 6–802

Design It Correctly

Reason with dependencies and remove insertion, update and deletion anomalies.

PART 3 β€’ LEVELS 9–1503

Query with SQL

Create, change and combine data with increasingly powerful SQL patterns.

PART 4 β€’ LEVELS 16–1804

Operate & Prove

Optimize, transact, recover, secure, build projects and prepare for interviews.

PART 1 β€’ LEVELS 1–5

Database Foundations

Build the mental models needed to understand every schema and query.

LEVEL 01πŸ—„οΈ

Database Foundations

Distinguish data, information, databases, DBMS software and traditional file systems.

  • Database characteristics and purpose
  • File-system limitations
  • DBMS users, roles and metadata
  • Real-world database examples
Open full lesson β†’
LEVEL 02πŸ›οΈ

Architecture & Data Models

See how users, applications, logical schemas and physical storage fit together.

  • Three-schema architecture
  • Logical and physical independence
  • Hierarchical, network and relational models
  • One-, two- and three-tier systems
Open full lesson β†’
LEVEL 03πŸ”—

ER Modelling

Turn real requirements into precise entities, attributes and relationships.

  • Keys and attribute types
  • Cardinality and participation
  • Weak entities
  • Specialization and generalization
Open full lesson β†’
LEVEL 04β–¦

Relational Model

Describe tables formally and choose keys that preserve identity and integrity.

  • Relations, tuples, attributes and domains
  • Super, candidate and primary keys
  • Foreign keys
  • Entity and referential integrity
Open full lesson β†’
LEVEL 05σπ

Relational Algebra

Build queries from formal operations and trace how intermediate relations change.

  • Selection and projection
  • Union, difference and product
  • Rename, joins and division
  • Expression and query-tree tracing
Open full lesson β†’
PART 2 β€’ LEVELS 6–8

Correct Database Design

Use dependencies and decomposition rules instead of memorizing normal forms.

LEVEL 06X→Y

Functional Dependencies

Express how attributes determine one another and calculate what a set can infer.

  • Trivial and non-trivial dependencies
  • Armstrong axioms
  • Attribute closure and candidate keys
  • Minimal cover
Open full lesson β†’
LEVEL 071β†’3

Normalization I

Diagnose repeating groups and dependency anomalies, then reach 1NF, 2NF and 3NF.

  • Insertion, update and deletion anomalies
  • Atomic values and 1NF
  • Partial dependency and 2NF
  • Transitive dependency and 3NF
Open full lesson β†’
LEVEL 08BCNF

Normalization II

Handle advanced dependencies and verify whether a decomposition is actually safe.

  • BCNF and 3NF comparison
  • Multivalued dependencies and 4NF
  • Join dependencies and 5NF
  • Lossless and dependency-preserving design
Open full lesson β†’
PART 3 β€’ LEVELS 9–15

SQL Mastery

Progress from valid statements to expressive, explainable and interview-ready queries.

LEVEL 09SQL

SQL Foundations

Read SQL syntax, understand its families and reason correctly about NULL.

  • SQL statement families
  • Identifiers and data types
  • NULL and three-valued logic
  • Portable SQL and dialect differences
Open full lesson β†’
LEVEL 10DDL

Database Definition

Create schemas and enforce valid data at the database boundary.

  • CREATE, ALTER, DROP and TRUNCATE
  • Primary and foreign keys
  • UNIQUE, CHECK and DEFAULT
  • Schema evolution decisions
Open full lesson β†’
LEVEL 11DML

Data Manipulation

Insert and change rows safely while predicting constraints and side effects.

  • Single and multi-row INSERT
  • Targeted UPDATE
  • Safe DELETE
  • MERGE/upsert patterns
Open full lesson β†’
LEVEL 12SELECT

Querying Data

Retrieve exactly the required rows and columns with precise filters and ordering.

  • SELECT and aliases
  • WHERE and compound predicates
  • LIKE, IN and BETWEEN
  • Sorting, limiting and CASE
Open full lesson β†’
LEVEL 13Ξ£

Functions & Grouping

Summarize rows, form meaningful groups and filter aggregated results.

  • Scalar and aggregate functions
  • GROUP BY reasoning
  • WHERE versus HAVING
  • Conditional aggregation
Open full lesson β†’
LEVEL 14β‹ˆ

Joins & Set Operations

Combine related tables without losing rows or accidentally multiplying them.

  • Inner and outer joins
  • Cross and self joins
  • Join-condition debugging
  • UNION, INTERSECT and EXCEPT
Open full lesson β†’
LEVEL 15WITH

Subqueries & Advanced SQL

Solve multi-step analytical problems and explain why each query layer exists.

  • Scalar, table and correlated subqueries
  • EXISTS, ANY and ALL
  • CTEs and recursion
  • Window functions and ranking
Open full lesson β†’
PART 4 β€’ LEVELS 16–19

Database Systems & Career Readiness

Connect SQL knowledge to performance, correctness, security and demonstrable project evidence.

LEVEL 16⚑

Views, Indexes & Optimization

Understand access paths and use query plans to improve slow SQL responsibly.

  • Views and materialized views
  • B+ tree and hash indexes
  • Sequential versus index scans
  • EXPLAIN and query optimization
Open full lesson β†’
LEVEL 17ACID

Transactions & Recovery

Keep concurrent changes correct and recoverable when operations fail.

  • ACID properties and schedules
  • Isolation anomalies
  • Locks, timestamps and deadlocks
  • Logging, checkpoints and recovery
Open full lesson β†’
LEVEL 18πŸ›‘οΈ

Security, Projects & Placement

Protect database access, build portfolio evidence and explain decisions in interviews.

  • Roles, privileges and SQL injection
  • Backup and operational responsibility
  • Three guided capstone projects
  • Interview, viva and placement revision
Open full lesson β†’
LEVEL 19πŸ›‘οΈ

DBMS & SQL Case Studies

Build complete real-world systems through design and query based case studies.

  • relational systems with constraints
  • with transactions
  • with testing and performance reasoning
Explore case studies β†’
INTERACTIVE LEARNING ROADMAP

Tools That Make Invisible Database Ideas Visible

Each lab will be introduced beside the concept it teachesβ€”not as a disconnected playground.

01

ER Diagram Builder

Translate requirements into entities, attributes, keys and cardinalities.

02

Closure & Key Calculator

Trace attribute closure step by step instead of accepting a black-box answer.

03

Normalization Assistant

Expose anomalies and verify each decomposition rule.

04

Relational Algebra Visualizer

Watch input relations become intermediate and final results.

05

Join & Query Tracer

See matches, unmatched rows, duplicates and logical execution order.

06

Transaction Simulator

Step through schedules, conflicts, locks, deadlocks and recovery.

LEARN WITH CONNECTED DATA

One Concept, Multiple Real Datasets

Examples will move beyond isolated employee tables. Students will compare the same idea across domains so they learn the pattern, not a memorized answer.

πŸŽ“ UniversityπŸ›’ E-commerceπŸ₯ Hospital🏦 BankingπŸ“š LibraryπŸ’Ό Recruitment
BUILD PROOF, NOT JUST NOTES

Three Portfolio-Ready Database Projects

FOUNDATION

Campus Course System

Requirements, ER design, relational mapping, constraints and reporting queries.

  • Students, courses and enrolments
  • Normalization evidence
  • Faculty and result reports
APPLIED

E-commerce Order Engine

Products, inventory, customers, payments, transactions and analytical SQL.

  • Order consistency rules
  • Index experiments
  • Sales dashboards
ADVANCED

Placement Analytics DB

Student skills, assessments, applications and recruiter-ready evidence.

  • Role-based security
  • Window-function reports
  • Performance explanation
ALREADY AVAILABLE

Continue into Placement Practice

Use the existing assessment tools while the full DBMS lesson series is built.

READ & REVISE

Database MCQ Library

Fast-reading and self-check material with explanations.

Open library β†’ ASSESS

Timed SQL Quiz

Complete the full session before answers and explanations unlock.

Start quiz β†’ EXECUTE

SQL Coding Arena

Solve judged database problems and inspect test outcomes.

Open arena β†’ REVIEW

Database Progress

See mastered questions, accuracy and your next practice direction.

View progress β†’