Question

Define foreign key how does it play role in the join operation

Answer 1

Answer:

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.

A JOIN is used when you extract/query data from the Database by giving rules how to select the data. Joins are used to merge data from two tables but Foreign Keys just refers to the Primary Key of another table to ensure that rows in one table have corresponding row in other table.