newbie needs help. Conditional relationship

[mike strong]

Hello all. I'm very new to Filemaker, and unfortunately I have been assigned a project to modify an existing FM6 file. Here's the breakdown. I'm going to have 3 files. One is Invoices, one is Customers, and one is Tax. I've created a relationship between Invoices and Customers, so that I can type in a customer number on the Invoices screen and have an auto-lookup to get the customer name, address, etc. No problem there. Now I need a way to take the City and Zip, and look up the tax rate in the Tax table. In itself, that might not be hard, but the kicker is I need to be able to account for misspellings in the City field, or some other strange happening, so that if the city/zip combo isn't found, I pull the highest tax rate for the zip only. It's a pretty hairy thing that I think I could do using if/then's, but since I don't really know what I'm doing, I'm not sure if it's a relationship setup or a lookup setup, or maybe both. Any help is appreciated.

Mike

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[RalphL]

You can reduce misspelling by using a popup. Have user enter zip code then provide a list of cities for that zip code.

You should use a lookup for the Tax Rate. A lookup does not change if you change the Tax Table. A related field would change and all your existing records would be messed up.

Lookup offer some special properties. Options to use a value when a match is not found is one of them.

[mike strong]

Okay, I think I follow you. I'll play around a little bit with that idea. Thanks!

Mike