Lecture 05: SQL Constraints Explained | NOT NULL, UNIQUE, PRIMARY, FOREIGN, CHECK, DEFAULT

🦉 Mastering Interviews While the World Sleeps ☕ | DBMS 05 – SQL Constraints | NOT NULL, UNIQUE, PRIMARY, FOREIGN, CHECK, DEFAULT Explained | Java Owl In this video, Level 5 of DBMS Interview Mastery - 6 Constraints that protect your database. Learn NOT NULL (no empty), UNIQUE (no duplicate), PRIMARY KEY (Boss - UNIQUE+NOT NULL + Only One), FOREIGN KEY (relationship chain - must exist in other table), CHECK (your custom rule age greater than or equals18), DEFAULT (auto fallback Patna) with live CREATE TABLE Student example and 4 live errors (1048, 1062, 3819, 1452) that save you from garbage data. Simple language, no textbook. 📌 In This Video ✅ What are Constraints? Security guard analogy ✅ NOT NULL – No empty allowed ✅ UNIQUE – No duplicate (1 NULL allowed) ✅ PRIMARY KEY – Boss Key ✅ FOREIGN KEY – Relationship lock + ON DELETE CASCADE ✅ CHECK – Custom condition ✅ DEFAULT – Auto fallback ✅ Live CREATE TABLE + Live Error Demo ✅ 5 Interview Qs – PK vs UNIQUE, FK NULL? 🔗 Useful Links 📄 Slides & Notes: https://drive.google.com/drive/folder... 📚 Full DBMS Playlist:    • DBMS Interview Preparation   💻 LeetCode: https://leetcode.com/u/vivekxsh/ ❤️ Support Like 👍 Subscribe 🔔 Share 📤 ⏳ Timestamps: 0:00 - Intro 0:38 - SQL Constraints 0:59 - What are Constraints 2:38 - Not Null Constraints 3:46 - Unique Constraints 5:05 - Primary Key Constraints 5:56 - Foreign Key Constraints 8:15 - Check Constraints 10:05 - Default Constraints 11:30 - All Constraints Use Case 14:40 - Interview Question 15:45 - End Happy Coding! 🚀 #dbms #sqlconstraints #primarykey #foreignkey #unique #notnull #check #default #dbmsinterview #sql #javaowl