Primary Key and Foreign Key
The CUSTOMER_ID in the order table becomes the foreign key that references parent or primary keys in the customer table. A unique constraint can be easily referenced by a foreign key constraint. How Do Databases Work Learn To Code Coding Ruby On Rails In this article I am going to discuss How to make Primary Key and Foreign key relationships between more than two tables in SQL Server. . SQL foreign key constraint is used to make sure the referential integrity of the data parent to match values in the child table. Table allows only one primary key. The following example describes that there is a table called student. In Table-1 Primary key Unique key Alternate key are a subset of Super Keys. A table can have multiple foreign keys. Please read our Primary Key. ALTER TABLE CUSTOMER ADD PRIMARY KEY ID. A FOREIGN KEY constraint does not have to be linked only to a PRIMARY KEY constraint in another table. Foreig...
