|Dropdown Listboxes and Datawindows are a great way of capturing valid
data and should always be used where possible. But there are limits.
The most amount of
data you should ever have in a drop down datawindow should be 200 rows.
Where possible never exceed this limit. There are two primary reasons. One is speed,
although this can be overcome with caching of the result set, the time still has to be
spent some where. The second and most important is that when you have a large number of
rows that little 6 row display areas become difficult for the user to manage. Scrolling to
the row they want may take some time, even with key stroke scrolling.
Where possible I would keep it to less than 100, less than 50 if you can swing it. Where
your foreign key data is greater than 100 rows you should use an edit field incase the
user knows the code and provide a separate lookup window with a tree view or search
criteria with a list Datawindow. It is easy to write a generic search Window that you can
use all over your application.