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Question
Differentiate Unique and Primary Key constraint.
Solution
| Unique Key Constraint | Primary Key Constraint |
| The constraint ensures that no two rows have the same value in the specified columns. | This constraint declares a field as a Primary Key which helps to uniquely identify a record. |
| The UNIQUE constraint can be applied only to fields that have also been declared as NOT NULL. | The Primary Key does not allow NULL values and therefore a field declared as Primary Key must have the NOT NULL constraint. |
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