What is diff between following relationship?
TableA:Site_id=TableB:Site_id and
TableB:Site_id=TableA:Site_id
Strictly speaking, the answer here is that there is no difference between the two lines.
In FileMaker, though, connections are between Table Occurrences
rather than between the tables themselves. The link between these Table Occurrences determines things like the sort order and whether a new record can be added directly to a related Table.
So, for instance:
TableOccurrenceA1::Site_id = TableOccurrenceB1::Site_id
and
TableOccurrenceA2::Site_id = TableOccurrenceB1::Site_id
Both link Table A to Table B, through Occurrences A1 = B1 and A2 = B1.
But the way these occurrences are set up can be different, even if the relationship is the same. So let us say that the relationship TableOccurrenceA1 = TableOccurrenceB1
is sorted by transaction date
in the descending
order, most recent dates first.
Let's also say that the relationship TableOccurrenceA2 = TableOccurrenceB1
is sorted by billing amount
in the descending
order, highest billed amounts first.
On a layout displaying TableOccurrenceB1, I could use the different Table Occurrences to display two different data points. For example, I could show the Most Recent Transaction by displaying field:
TableOccurrenceA1::transaction date
I could show the Largest Transaction by displaying the field:
TableOccurrenceA2::billing amount
Note that we're using the sort order set in the relationship diagram to automatically pull only the one value that we want, based on two different Table Occurrences of TableA with the same relationship.