Hello all!

How does one design a table that will for example store information about members. These members can only be a member of one club or another club, but not both.
How does one implement such a control into a table.

Thanks in advance

CREATE TABLE clubs
( club_id INTEGER NOT NULL PRIMARY KEY
, club_name VARCHAR(255)
);
CREATE TABLE members
( member_id INTEGER NOT NULL PRIMARY KEY
, club_id INTEGER NULL
, CONSTRAINT member_club_fk FOREIGN KEY ( club_id ) REFERENCES clubs (club_id)
, member_name VARCHAR(127)
);

By giving the table a key (uniqueness constraint). If you are serious about learning then I suggest you read a decent introduction and study some basic principles rather than jump straight into design problems. If you have a particular example in mind then post that example.