Re: Help to design relations between some 5 tables with possible many-to-many relations
| От | David G. Johnston |
|---|---|
| Тема | Re: Help to design relations between some 5 tables with possible many-to-many relations |
| Дата | |
| Msg-id | CAKFQuwbe9iokBFSM+qt0-Eh1GHDp=S7+jw=bBJUoTuJMWBkW7Q@mail.gmail.com обсуждение исходный текст |
| Ответ на | Help to design relations between some 5 tables with possible many-to-many relations (JORGE MALDONADO <jorgemal1960@gmail.com>) |
| Список | pgsql-sql |
On Mon, Jun 21, 2021 at 12:07 PM JORGE MALDONADO <jorgemal1960@gmail.com> wrote:
Hi,I have the following tables: reports, standards, elements, tables, items.* One report has many standards.* One standard has many elements.* One element has many tables.* One table has many items.[...]I see that many-to-many relations exist between all of the tables but I am not able to clearly visualize.
From my perspective the fundamental decision you need to make is whether to indeed deal with many-to-many relationships or just deal with one-to-many relationships. In the later case you have 5 entities and 4 relationships and thus you will have 9 tables. If you can force one-to-many relationships then you only need 5 tables, with the four "right side" tables having a FK to the corresponding "left side" table.
Personally, I would go with one-to-many relationships and just "clone" anything that is going to be the same from one year to the next.
David J.
В списке pgsql-sql по дате отправления: