Thread: question : the choice of the primary key.

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.

> 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

i solved it for now
using a p-key (the short id)
and a a-key (the natural key),
so integrity is ok and refences are short.

>
> u have often this choice in determining the primary keys,
>
> plz give me your opinions, options i overlooked or usefull comments.
>
>