Dropdown Query

[Tatty]

I am new to Filemaker so apologies if this query is a bit basic.

I have a form based on a tblExpenses which contains transactional data. Within that table there is (for example) a field called CategoryID. This relates to a CatID field in a seperate tblCategories. What I want is a way on the original form that when the user tabs in, they can start typing the category description but be restricted to that values from tblCategories.The resultant value though needs to be stored as the ID (not the description) in the tblExpenses

I've tried using drop downs and pop ups but this doesn't seem to meet the requirement. What I think I need is an edit box which auto completes against a value list from the tblCategories.

I could do it by storing the descriptions (rather than IDs) in the table but this goes against what I've been taught about having unique numerical IDs for each category.

Any ideas? Thanks in advance

Tatty

[comment]

Please do not double-post:

http://fmforums.com/forum/topic/79334-relational-tables/