2 versions of an entity worth distinct table?
If a table representing contact details can have 2 but no more than 2 email addresses is it really worth factoring-out email addresses to a separate table. Technically it's a 1-to-many relationship so should be done this way but what is the general practice out there in such "max. 2" situations? Keeping them as:
Primary Email
Secondary Email
.... also preserves priority though not strictly normalised, I know.
gvim
Hi,
In this particular case it isn't worth to add separate table just for
additional e-mail.
gvim <gvimrc@gmail.com> Monday 27 December 2010 02:47:29
Show quoted text
If a table representing contact details can have 2 but no more than 2 email
addresses is it really worth factoring-out email addresses to a separate
table. Technically it's a 1-to-many relationship so should be done this
way but what is the general practice out there in such "max. 2"
situations? Keeping them as:Primary Email
Secondary Email.... also preserves priority though not strictly normalised, I know.
gvim
gvim wrote on 27.12.2010 02:47:
If a table representing contact details can have 2 but no more than 2
email addresses is it really worth factoring-out email addresses to a
separate table.
If you are absolutely sure you will never have more than two, then I agree, you don't need to create a 1:N relationship for that.
Especially because guaranteeing that there will never be more than two in the N part is quite complicated.
Regards
Thomas
But then a) because you can't guarantee this design won't 'improve' and
b) you would like to look in one place for all addresses, normalize now.
Thomas Kellerer wrote:
Show quoted text
gvim wrote on 27.12.2010 02:47:
If a table representing contact details can have 2 but no more than 2
email addresses is it really worth factoring-out email addresses to a
separate table.If you are absolutely sure you will never have more than two, then I
agree, you don't need to create a 1:N relationship for that.
Especially because guaranteeing that there will never be more than two
in the N part is quite complicated.Regards
Thomas
gvimrc@gmail.com (gvim) writes:
If a table representing contact details can have 2 but no more than 2 email addresses is it really worth factoring-out email addresses to a separate table. Technically it's a 1-to-many relationship so should be done this way but what is the general practice out there in such "max. 2" situations? Keeping them as:
Primary Email
Secondary Email.... also preserves priority though not strictly normalised, I know.
I'd be inclined to normalize this, as it's:
a) difficult to guarantee that it will only ever be 2.
b) mighty nice to be able to attach validation rules to ONE simple email
table, rather than having to put them on several columns possibly
spread across more tables.
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