Question

What is the purpose of the SQL keyword PRIMARY KEY?

1) To designate the column(s) that are the primary key for the table
2) To specify the data type of the column(s) in the table
3) To define a foreign key constraint in the table
4) To create an index on the column(s) in the table

Answer 1

The purpose of the SQL keyword PRIMARY KEY is to designate the column(s) as the unique identifier for each record within the table, ensuring data integrity and creating an index to improve search operations.

Step-by-step explanation:

The purpose of the SQL keyword PRIMARY KEY is to designate the column(s) that are the primary key for the table. The primary key is a unique identifier for each record in the table, ensuring that no two rows can have the same primary key value. This helps maintain the integrity of the data within the table. The primary key also automatically creates an index on the column(s), which improves the speed of search and retrieval operations. However, the creation of an index is a consequence of defining a primary key, and not the primary purpose of the PRIMARY KEY keyword.

It should be noted that the PRIMARY KEY keyword does not specify the data type of the column, nor does it define a foreign key constraint; other SQL commands are used for these purposes.