Question

What is a primary key? CBSE 2003
Or
Define primary key with an example. CBSE 2005
Or
What is primary key? Give an example. CBSE 2007
Or
What is a primary key in database? Give an example. CBSE 2010

Answer 1

A primary key, also called a primary keyword, is a key in a relational database that is unique for each record. It is a unique identifier, such as a driver license number, telephone number (including area code), or vehicle identification number (VIN). A relational database must always have one and only one primary key.

A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records. A primary key's main features are: It must contain a unique value for each row of data. It cannot contain null values.

Answer 2

$\huge{\underline{\underline{\cal{\color{purple}{ʕAnswerʔ}}}}}$

$\sf{\underline{\red{Primary Key ➳}}}$

Primary Key is a field in a table which uniquely identifies each row/record in a database table.

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