🔑 Primary Key: The Ultimate Row ID in SQL! #DatabaseBasics

A Primary Key (PK) is the unique fingerprint for every table row:

✔️ 100% Unique – No duplicate values allowed
✔️ Mandatory – Never NULL (unlike other columns)
✔️ Speeds Up Queries – Auto-creates an index

*Example:*
```sql
CREATE TABLE students (
student_id NUMBER PRIMARY KEY, -- ← PK!
name VARCHAR2(100)
);
```

💡 *Pro Tip:* Use `AUTO_INCREMENT` (or sequences) for hassle-free PKs!

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