Define a Foreign Key.

Q. Define a Foreign Key.

Answer =

A foreign key is a key which is used to link two tables together. It is also called a referencing key. Foreign key is a column or a combination of columns whose values match a primary key in a different table. The relationship between two tables matches the primary key in one of the tables with a foreign key in the second table. If a table has a primary key defined on any field(s), then you cannot have two records having the same value of that field(s).