CONSTRAINTS

✅ Constraints in Data Bases are used to define and Integrity Constraint, as a rule that restricts the values in a data base.

OR (in other words)

In Oracle CONSTRAINT clause allows you to restrict the date, that is entered into a column to ensure that it is valid or that is meets certain conditions.

Or 

Constraints are rules applied on table columns  to maintain accurate & valid data

Types of Constraints :--

1. NOT NULL Constraint : Prevent NULL Values
2. UNIQUE Constraint : No duplicate Values
3. CHECK Constraint : Apply Condition
4. PRIMARY KEY Constraint : Unique Identifier
5. FOREIGN KEY Constraint : Create Relationship
6. Default Constraint : Set default value

⚡  Why Use Constraints?  

✔️ Prevent invalid data  

✔️ Maintain consistency  

✔️ Improve data integrity  

✔️ Enforce relationships  

Scenarios for Practice Tasks  

1. Create table using PRIMARY KEY  

2. Add UNIQUE constraint on email  

3. Create FOREIGN KEY relationship  

4. Use CHECK for salary > 0  

5. Add DEFAULT city value  

⚡ Mini Challenge 🔥  

👉 Create students table with:  

- student_id → PRIMARY KEY  

- email → UNIQUE  

- age > 18 using CHECK  

- city default = 'Mumbai'

#constrains #constrains_in_oracle #oracle_constraints