Referential Integrity Constraint

This constraint establishes the relationship among tables. A single or combination of columns that can be associated to the other tables is used to perform this type of operation. Foreign key is used to establish the relationship among them. This kind of relationship can be referred to as a Parent-Child relationship. The table holding the referenced key from where other tables refer for values is known as the Parent table and the table containing the foreign key is known as the child table.