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प्रश्न
Write a short note on Primary key constraints.
टिप्पणी लिखिए
उत्तर
Primary Constraint:
- Primly Constraint declares a field as a Primary key which helps to uniquely identify a recor<}ll
- Primary Constraint is similar to a unique constraint except that only one field of a table can be set as the primary key.
- The primary key does not allow NULL values and therefore a field declared as the primary key must have the NOT NULL constraint.
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