I have a dowloaded flat file table of realtor sales performance.
I want to make one portal summarizing listings sold, and another summarizing buyer transactions.
How does one do this with only one table of data?
Get familiar with the way FileMaker accesses data in tables: it works not directly via tables, but via the TOs (table occurrences) that you create for your tables in the Relationship Graph.
A portal shows records from another TO that is (directly or indirectly) related to the TO of the current layout. In the Relationship Graph, you can create any number of TOs for your tables (even if you only have a single one).
You can create multiple TOs and relate them to your layout's TO using different predicates (match fields) – or, depending on the amount of data, create one related TO and filter your portals (which is often easier to implement since you can use non-indexed data on the “data side” to define your filter, but has worse performance than a relationship-level filter).
Of course, in the long run it may be worth your while to convert your flat-file structure into a proper relational setup.
you are after a self relationship, the flat file is a single table, and that 'base table' is represented in the relationship graph (RG) as a table occurance (TOC)
you can have more than one TOC representation of a base table in the RG
so differenet self relationships, using appropriate predicates ( left field= right field; pair) would be used to display different data in respective portals.
However, as erolst suggested, a flat file may be only of short time benefit.
I would go further and suggest a flat file is a waste of time, for the functionality required by a property/sales database, in the real world.
See if this works for you - by adding a single global field and a TO, you have a mini Viewer the likes of the session model.
A next step would probably come with you wanting to have the detail view display for each record selected on click within the portal.
This approach is right inline with going that direction. That (or really much expansion at all) would be the point you would want to add a VIEWER table to give a home to the various non data fields generally involved in making a dashboard type user interface in filemaker.
Retrieving data ...