I have a drop down list box that is populated from a seconday data connection
to a SQL server database.  When it populates I would like it to remove
duplicate entries.  A trawl of the internet came up with the solution:

. = (. = not(. = preceding::my:field))

The dropdown list box is based on a field query field called ChecklistGroup
so I used the formula:

. = (. = not(. = preceding::q:ChecklistGroup))

and put it on the data connection filter.  This didn't do anything so I
tried to add it as a rule of the listbox.  This didn't work either.

Can anyone suggest either what I am doing wrong or if there is a way of
doing this?

Thanks