What is foreign key ? How do you define a foreign key in your table ?

Q. What is foreign key ? How do you define a foreign key in your table?

Answer =

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.

A FOREIGN KEY is a key used to link two tables together.

A FOREIGN KEY is a field (or collection of fields) in one table that refers to the PRIMARY KEY in another table.

Foreign key ( <column name>) REFERENCES <parent table name > ( < Column name  > )