topic Re: Data dictionary : multiple foreign keys in Application Development and Automation Discussions

Data dictionary : multiple foreign keys

dhorions — Fri, 24 Aug 2007 08:20:43 GMT

Hello,

can anyone tell me how I assign more than 1 foreign key to a table for the same field?

Is that even possible?

I created a diagram of what I want to achieve, I hope this is clear, if not, just ask.

<a href="http://www.quodlibet.be/files/foreign_key.jpg">figure</a>

Re: Data dictionary : multiple foreign keys

Former Member — Fri, 24 Aug 2007 08:24:08 GMT

well you gotta work the other way round. your tables child_a and child_b nood to implement that field and have it marked as foreign key.

Re: Data dictionary : multiple foreign keys

dhorions — Fri, 24 Aug 2007 08:26:52 GMT

I tried that, but then I got an error message when I tried to insert a new record to my 'main' table, saying it didn't exist in the other table.

But I'll check it again just to make sure.

Thnx.

Re: Data dictionary : multiple foreign keys

Former Member — Fri, 24 Aug 2007 08:32:45 GMT

yes you can creat

for example

MARA, MARC,MARD

these 3 tables having MATNR field as the same

MARD and MARC are the two tables which having FK relation to MARA

try this

reward if usefull

Re: Data dictionary : multiple foreign keys

Former Member — Fri, 24 Aug 2007 08:33:23 GMT

yeah that is the relational data model.

you can not create a record which has a reference to something that doesnt exist.

e.G. in an sales order, we have a field for customer. well you cant create a sales order and fill in a customer that doesnt exist.

thats exactly the thing for which foreigh keys are made.

Re: Data dictionary : multiple foreign keys

dhorions — Fri, 24 Aug 2007 08:35:38 GMT

You get me wrong, what I am saying is that it should be possible to create a customer if a sales order does not exist, but like I said, i'll just double check if I didn't make any mistakes.

Thanks anyway.

Re: Data dictionary : multiple foreign keys

dhorions — Fri, 24 Aug 2007 09:07:09 GMT

I don't seem to get it right,

I have three tables, like in the figure in my initial post.

In table CHILD_A I create a foreign key (with check required) linked to the field ID in the table MAIN.

When I add a new record to the table MAIN, I get the error message that I defined in the foreign key.

What I expected was this error to occur when I added a field to table CHILD_A that didn't have a corresponding record in table MAIN.

Re: Data dictionary : multiple foreign keys

Former Member — Fri, 24 Aug 2007 09:09:52 GMT

hmmm ok, thnen i lost overview, maybe you goto the Tables MARA, MARC, MARD, MARM and check how they have solved the issue there.

Re: Data dictionary : multiple foreign keys

dhorions — Fri, 24 Aug 2007 09:43:47 GMT

After triple-checking my program, I found that the problem only occured when I had a search help linked to that field on my screen.

So it does work like I suspected, and like you guys said it would, but the check was more severe than I thought.

Thank you all.