Question

Let’s suppose I have a table of roles, for example,

Roles
-----
ID  Name
0   Salesman
1   Client
2   Manager

Let’s also suppose that these roles are not mutually exclusive: that is, a person can be a salesman, a client, and a manager all at the same time.

If I have a Person table with a Role field, how am I able to reference multiple rows in the Roles table?

Answer 1

You introduce a new table that references both of the original tables:

CREATE TABLE PersonRoles (
    PersonID int not null,
    RoleID int not null,
    constraint PK_PersonRoles PRIMARY KEY (PersonID,RoleID),
    constraint FK_PersonRoles_Persons FOREIGN KEY (PersonID) references Person (ID),
    constraint FK_PersonRoles_Roles FOREIGN KEY (RoleID) references Role (ID)
)

Assuming that the multiplicity is m:n, the above is correct. I made the assumption (not listed in your question) that more than one person can be e.g. a Salesman.