For example, the "Doctor Last Name" field might be assigned as a primary key of the Doctor table with all people having same last name organized alphabetically according to the first three letters of their first name. A table can also have a foreign key which indicates that  field is linked to the primary key of another table.
Consider an example where "Doctor Last Name" serves as the primary key in the Doctor table, grouping individuals with identical last names alphabetically by their first three letters. Additionally, a table might include a foreign key pointing to the primary key of another table.