|
Not necessarily. I BELIEVE - but I haven't tested
this, that if you had 3 tables, Table 1 in one to many to Table 2 and Table 1 in
one to many with Table 3, that this would be ONE to MANY
MANY to MANY means more than one level of
relationships
Table 1 one to many with Table 2
Table 2 one to many with Table 3
David
----- Original Message -----
From: Michael Moser
Sent: Saturday, March 12, 2005 3:22 PM
Subject: [RBG7-L] - Re: When is a one to many form appropriate wtih
3 tables Hi David,
Thank you, that makes sense.
Just to clarify then in this context, in any normalized data
schema situation any form with more than 2 tables is going to be a
many-to-many form in R:Base 7. This is true because 3 or more tables
will always have "many (more than one) one-to-many" relationships.
yes?
Thanks,
Michael
Michael Moser EXAQ Micro Services www.exaq.com Phone: 916-966-8313 Fax: 916-966-8313 >> Michael In 7.x, the term "Many to Many" on the form properties screen is >> not used in the classical relational database meaning. You have MULTIPLE >> one to many relationships and so in 7.x you should use the "Many to >> Many" setting (it really should read >> "Multiple One to Many" but who's quibbling!) David Blocker >> [EMAIL PROTECTED] >> 781-784-1919 >> Fax: 781-784-1860 >> Cell: 339-206-0261 ----- Original Message ----- From: Michael Moser To: >! > RBG7-L Mailing List Sent: Saturday, March 12, 2005 11:38 AM Subject: >> [RBG7-L] - When is a one to many form appropriate wtih 3 tables >> Hi All, >> I just joined the list server so this topic may have been addressed in >> the past. If so I beg your indulgence one more time... I am trying to >> understand when to use the one-to-many setting and when to use the >> many-to-many setting in the form properties >> when using R:Base 7.1 forms With two tables, A and B, with a one-to-many >> (<) relationship between the two (A<B), the form properties are set to >> one-to-many and the form works correctly. How ever if three tables are >> used (A, B, and C) such that: >> ! Table A has a Primary Key Table B has a Primary Key and a! Foreign Key to A >> Table C has a Primary Key and a Foreign Key to B Table A and Table C have >> no common fields Thus creating a one-to-many relationship between A and >> B, and a one-to-many >> relationship between B and C (A<B<C). If a view AB was created from >> tables A and B, the view would also have a one-to-many relationship with >> table C (AB<C) It seems that a form using A, B, and C would still be >> configured as one-to-many but in fact it >> must be set to many-to-many in order to work properly. Setting the form >> to one-to-many with Tables A, B, and C causes the correct record set to >> be displayed for B, but all records are displayed for C. So my question >> is this. &n! bsp;Can anyone provide an >> example of 3 tables that would use the one-to-many setting in a form? >> Perhaps my understanding of one-to-many is inaccurate and all forms using >> 3 or more tables are many-to-many by definition, regardless of the >> relationships between the tables. >> Thanks, Michael >> Michael Moser >> EXAQ Micro Services >> www.exaq.com >> Phone: 916-966-8313 >> Fax: 916-966-8313 |
