Software Architect's Handbook

Identifying primary and foreign keys

All of the primary and foreign keys for all of the tables in the database should be identified. The primary key of a table is the column, or combination of columns, that uniquely identify a row in the table.

Sometimes a row in a table must reference a row from another table. A foreign key is a column or combination of columns that hold the primary key value for a row in another table so that it can be referenced.

Database constraints based on the primary and foreign keys should be created to enforce data integrity. A primary key constraint for a table consists of the one or more columns that make up the primary key and a foreign key constraint consists of the one or more columns that make up the foreign ...