Surrogate Keys in RDB’s
The unique pkey which selects this section of OOAD in the Student Information System (SIS) Database is a composite of Dept, Course and Sectio number: 91.522.201.
For IBM’s RDB, EFCodd advocated a hidden ‘surrogate’ pkey to replace the user-defined composite keys. This improves code quality and performance (by expediting the fundamental RDB operation ‘join’: match pkeys to fkeys).
Example: Entity with old and new key name and value:
Entity: alternate (old pkey): surrogate (name = value):
Dept deptNo = 91 DEid = DE000001
Course courseNo = 91+522 COid = CO000220
Section sectNo= 91+522+201 SEid = SE002601