Keys & Constraints in SQL Explained | Primary Key, Foreign Key, Unique Key & Relationships

Master SQL Keys & Constraints with simple real-world examples! In this video, you'll learn everything you need to know about SQL Keys, Relationships, and Constraints before moving into hands-on SQL coding. 📌 Topics Covered: ✅ Primary Key ✅ Composite Primary Key ✅ Candidate Key ✅ Unique Key ✅ Foreign Key ✅ One-to-One Relationship ✅ One-to-Many Relationship ✅ Many-to-One Relationship ✅ Many-to-Many Relationship ✅ Self-Referencing Relationship ✅ NOT NULL Constraint ✅ CHECK Constraint ✅ DEFAULT Constraint ✅ Column-Level vs Table-Level Constraints This video is part of my complete SQL course for beginners where we learn SQL using real-world examples instead of boring student databases. Whether you're preparing for SQL interviews, Data Engineering, Data Analytics, Software Engineering, or Database Administration, this lesson will build a strong foundation. In upcoming videos, we'll implement all these concepts practically using PostgreSQL. If this video helped you, please Like, Share and Subscribe to *The Code Brat* for more SQL tutorials. #SQL #Database #PostgreSQL #DDL #DataEngineering