I need help creating a combo box in a form in base

[zipster1967]

I am using LibraOffice version 4.4.3.2 Base

I have a table for categories with 3 fields The ID field a category field and a parent category field.
The parent category field contain the ID of the table record for the category I want listed as the parent of the category of the current record. For example:
ID Category Parent Category
0 Meat -NULL-
1 Frozen -NULL-
2 Fresh -NULL-
3 Fruit 2
4 Fruit 1

So if I wanted an item listed as being in the Fresh Fruit category it would have a category in the items table of 3 But I am not sure how to create a combo box for the parent category field in a form to let me select a category from the table in the parent category field. Can anyone help me accomplish this?

[JohnSUN]

Did you mean something like this?

SELECT DISTINCT "Name", "ID" FROM
  (SELECT "CategoryID" "ID", "CategoryName" "Name" 
     FROM "Categories"
     WHERE ("ParentID" IS NULL) 
 UNION ALL
   SELECT "A_2"."CategoryID" "ID", "A_2"."CategoryName" "Name" 
     FROM "Categories" "A_1", "Categories" "A_2" 
     WHERE "A_2"."CategoryID" = "A_1"."ParentID") 

So, if you insert something as “8-Apple-4” then you can see subcategory “Fruit” from category “Frozen” in the list.

NB. It must be ListBox, not ComboBox! Set this SELECT to “List content” of this control