Which of the following describe the Primary key?
Correct answer: D. All of these
- A. It must be unique
- B. It helps in indexing of large database
- C. It makes sorting quicker
- D. All of these
Explanation
A primary key is a column (or set of columns) in a database table that uniquely identifies each row in the table. This means that no two rows in the table can have the same value for the primary key.B. It helps in indexing of large database: A primary key can be used to create an index on a table, which can improve the performance of queries that filter or sort data based on the primary key. However, this is not the only purpose of a primary key.C. It makes sorting quicker: As mentioned above, a primary key can be used to create an index that can speed up sorting.
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