URGENT!!!! Category and Sub-Category

[hud]

I would like when a user selects a option from the category listing, only the sub-category display when selecting a sub category.

Category: Development
Sub Category: (List only those that are associated with Development category, not the entire Sub-category listings).

Thanks.

 

[NeilDT]

Field: PDR_ProductGroup
Keyword, Use formula for choices - 1st level.
@Unique(@DbColumn("":"";"";"Tables\\Level1";2))

Field: PDR_SubProductGroup
Keyword, Use formula for choices - 2nd level.
@Unique(@DbLookup( "";"":"";"Tables\\Level1"; @Trim(PDR_ProductGroup); 3))

Tables\\Level1 has columns for:
Hidden key , Product Group, Sub Product