Cam sexy teen video web - Updating the primary key
Some possible examples of unique keys are Social Security Numbers, ISBNs, vehicle registration numbers or user login names.
The relational model, as expressed through relational calculus and relational algebra, does not distinguish between primary keys and other kinds of keys.
Here is an example of a primary key becoming a foreign key on a related table.
ID migrates from the Author table to the Book table.
Keys that migrate to another entity may or may not be unique, depending on the design and how they are used in the other table.