From Dwayne Wright PMP
Certified FileMaker Developer
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Generally speaking, the most common FileMaker table relationship is when a field in this table equals a field in that table. In fact, prior to FileMaker 7, that was all you can do. With the more modern versions of FileMaker, you can setup multiple predicate relationships using more than two fields and operators other than equal to.
However, there was a technique before FileMaker 7 that kind of allowed developers to use multiple fields in a relationship. One of the two fields was actually a calculation field that was made up of many fields.
But what if you wanted to compare one field but have more than one key value?
A multiple value key field is a great way to setup a many to many relationship. In fact, prior to FileMaker 7, it was the only real way to setup a many to many relationship. It all hinges on the values in the key fields being separated by a carriage return. These carriage return separated data strings are considered their own related values.
That is to say if the parent key field contains
and the child key field contains Yellow ... you have a valid relationship! You also have a valid relationship to another record that only contains Red in the child field.
To take it even a step further, it’s possible that a value that is separated by a carriage return in one key field matches a value separated by a carriage return in the other key field, the relationship is valid. That is to say if the parent key field contains
it will have a valid relationship to the child Key field containing the value of
This is because the carriage returned data string of “Yellow” appears in both key fields.
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© 2007 - Dwayne Wright - dwaynewright.com
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