Question

Define the following:
a. Primary Key
b. Foreign Key

Answer 1

Answer:

Primary key is unique value that identifies a row in a table. Foreign key identifies a column or a set of columns in one table that refers to a column or a set of columns in another table.

Answer 2

Answer:

a. Primary key –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.

b. Foreign key– A foreign key is a column or group of columns in a relational database table that provides a link between data in two tables. It acts as a cross-reference between tables because it references the primary key of another table, thereby establishing a link between them.