U have for example something like this create table persons( (id..), surename .., familyname .., street .., .., birthdate,.. )
a table containing the data of persons, each persons should of course be present only once; and one should still define a primary key, there are two options now, 1.many people make an extra id field and choose this id field to be the p-key, but then the same person can be present twice in the table (with different id fields), the id in itself has no real meaning 2.or u can choose the "natural" key for each person, lets say a name and the birthdate of a person make that person unique, so lets make (the whole name en the birthdate) the primary-key; but then if another table X wants to refer this table of persons using a foreign key, this foreign key exists out of 3 fields, which smells redundant u have often this choice in determining the primary keys, plz give me your opinions, options i overlooked or usefull comments. ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
