Linking to Other Forms – What kind of join?

[Carol Jones]

I have a main form (parent form) containing names and other information on members of our organization.
I have another form (child form) that contains payments and donations they have made.

I have a “link to form” field in the parent form that lets us enter the amount paid and the check number or payment type, the date, type of membership, etc..

When we enter data into this link to form field, it creates entries in the child form, as we expect. This is good. I chose to make that link type a “join” on the full name field.

However, if one person makes more than one payment, this ads a separate record in the child form so when we are trying to find out how many people have paid, the results are spurious.

Should I have made the link-to-form field a “one to many” link instead? If so, can I change it without messing up all the data that is already in the child form?

I also have a “Show Inverse Relationship” field in the child form. I think this is good, but not sure.

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One reason this concerns me now is that am importing another child form that is a list of data about some of these same people, plus more, concerning a specific project we are working on that is eventually to be exported out and become data for creating a printed book. I am wondering what type of relationship that should be to the parent form. Or should the parent/main form become the Child of this new form I will be importing?

[Brendan]

Hi Carol,

If you change a Join Link Type to a one-to-many or many-to-many, you’ll have to manually re-establish the relationships. The Join and the other two work very differently internally and are not really compatible in that sense. Although the Join one behaves much like a many-to-many Link Type because you can have multiple child records with multiple parent records.

You can certainly change it and it won’t mess up the data in either form. You’ll just have to go through everything one-by-one to re-establish the relationships.

One thing you can do to experiment with alternate relationship types is to use the Duplicate Document function to make a full copy of your document, then play around with the relationships in the copy to see which one works best for your use case. That way you don’t end up inadvertently modifying the original, especially if you’re syncing the original with other devices. Since the duplicate document will be assigned a new unique Document ID, it won’t affect syncing. But you MUST use Tap Form’s Duplicate Document function. Don’t just duplicate the .tapforms file in the Finder. If you do that, you will mess up your original during the sync process.

Thanks,

Brendan

[Carol Jones]

Thank you. That is very helpful. I’m experimenting by adding other simple forms with fewer fields and creating different kinds of linking fields that I can modify with this shorter and simpler data rather than recreate the whole database. But thank you for pointing out the ability to do that and how to. Now I am so immersed in fiddling with various join types that I am a bit overwhelmed. I know I will get it soon. Meanwhile thank you so much for your help. You are truly a database genius.

[Author]

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