Re: many-to-one relationship

oracle8i supports the use of variables for table names in a FROM clause. using a string value from a column representing a table name is trivial.

"Sam Staton" <sam.staton_at_bigfoot.com> wrote in message news:5psahtg62tg613kllhjdano3k9fsgvaa0i_at_4ax.com...
> As I suggested.
>
> This will work fine, as long as you do not need to obtain the
> SomeTableX row which corresponds to a particular NoteTable record (I
> guess you are not likely to need to do this anyway).
>
> For this you will need to do a messy union, as previously mentioned.
>
>
> On Wed, 30 May 2001 18:08:22 -0400, "Steve Long"
> <steven.long_at_erols.maps_on.com> wrote:
>
> >this is quite easy.
> >
> >create sequence noteID_seq; -- produces a unique note_id for every note
 in
> >the database.
> >create sequence someID_seq -- produces a unique ID for every 'something'
 in
> >the database
> >
> >SomeTable1 (..., someID, ...) -- data table for some data with or
 without
> >notes
> >SomeTable2 (..., someID, ...) -- another data table for some data with
 or
> >without notes
> >...
> >SomeTableN (..., someID, ...) -- another data table for some data with or
> >without notes
> >
> >NoteTable (someID, noteID, ...) -- table containing all notes
> >
> >Any insert statements to SomeTables shoud use someID_seq.nextval and
> >noteID_seq.nextval for the respective ID values.
> >Whenever a row is inserted into SomeTable which has a note, a
 correpsonding
> >entry in NoteTable should be made.
> >
> >It is important to remember the "parent-child" relationship. A common
> >mistake is forgetting that in a relational model, the
> >parent table does not require any knowledge of the child table. This
> >structure is very similar to a "bill-of-materials" or
> >invoice structure where there is a master table containing header
> >information and then a line-item table containing each
> >of the line items associated with a given master element.
> >
> >"Steve Croft" <stevec_at_ditdash.com> wrote in message
> >news:3B1084AA.3060902_at_ditdash.com...
> >> I am having a rather sticky modeling problem. We have a number of
> >> different tables, rows of which may have zero, one or more notes
> >> attached. A note table has a type id indicating the table, and an id
> >> indicating the row in that particular table.
> >>
> >> I suspect there is a better way to do this - is there? If not, how do
> >> you diagram it?
> >> I'm sure it's an obvious answer but I'm not seeing it :(
> >>
> >> Thanks in advance,
> >> Steve
> >>
> >
>
Received on Sun Jul 22 2001 - 01:27:22 CEST