Why Integrity Constraints? – Database Management System (DBMS)

Integrity Constraints are rules applied to database tables to ensure the accuracy, consistency, and reliability of data. They prevent invalid or illogical data from being entered into the database.

✅ Purpose of Integrity Constraints:

🎯 Goal	📖 Explanation
✅ Data Accuracy	Prevents incorrect or contradictory data from being inserted
🔄 Data Consistency	Maintains uniformity and logical correctness across related tables
🚫 Avoid Invalid Data	Stops nulls or duplicates where they're not allowed
🔗 Maintain Relationships	Ensures linked records exist (e.g., student must belong to a valid department)
🔒 Enforce Business Rules	Applies real-world logic, like a product must have a positive price

🛠️ Types of Integrity Constraints:

🔐 Constraint Type	🌟 Ensures That...
Primary Key	Each row is uniquely identifiable and not null
Foreign Key	Data in one table must match existing data in another
Unique	Column values are distinct (but can be null once)
Not Null	No empty (null) values are allowed
Check	Column values must satisfy a specific condition
Default	Sets a default value if none is provided

💡 Real-Life Analogy:

Imagine filling a college admission form:

You must provide your name → NOT NULL
Your ID must be unique → PRIMARY KEY
You must select a valid course from a list → FOREIGN KEY
Your age must be >= 17 → CHECK constraint