Aug 3, 2022
इस लेख "Composite key in DBMS in Hindi" में, उदाहरण के साथ जानिए समग्र कुंजी क्या है (What is Composite key in Hindi) पूरी जानकारी हिंदी में।
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इस लेख "Composite key in DBMS in Hindi" में, उदाहरण के साथ जानिए समग्र कुंजी क्या है (What is Composite key in Hindi) पूरी जानकारी हिंदी में।
Sometimes more than one attribute needs to create a key that uniquely represents a tuple. That keys are known as a composite key or compound key.
Purpose of a Primary Key
I recently replied to Quora questions What is the use of a primary key and How is the Primary Key different from a Unique Key?
Unique Key
A Unique Key is used when you want to prevent duplicate values; i.e. to impose the uniqueness constraint. There can be multiple unique keys in a table. The uniqueness constraint means only ONE row can have a NULL in the Unique Key. Otherwise there would be…
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