Query for ComboBox - Show each entry only once

[Guest]

I have a table of categories with Primary Category and Secondary Category and
Category ID. Category ID is one to many with Product Table. Primary
Category has 4 entries that are reentered for around 8 subcategories. I
would like to use a dropdown menu combobox in a form to input the Primary
Category. Is it possible to query the table for each unique entry in that
field, or do I need to separate my category table into two tables? (I have
been using a value list, but now I want to have a subform to add a category
and any changes to the category table won't be reflected in the value list.)

 

[Tom Ellison]

Dear McLitle:

In your table of categories, you have multiple rows with the same Primary
Category value? Is that a good thing?

Of what entity is this a table?

Is there a reason you do not have a table of Categories (or Primary
Categories) in which each category is placed only once?

Tom Ellison

 

[Guest]

Not every Primary Category has a Secondary Category so when I built the
database, I just created one Table. CategoryID (one to many to Product
Table) Primary Category with a value list and Secondary Category that is
text. This way each combination (even one with no entry into Secondary
Category) would have a CategoryID. Is there query that is similar to the
Auto Filter in Excel? One that I can put in the rowsource for PrimaryCategory
in a form. I have already completed the form so that it looks up the
CategoryID based on the entry into fields PrimaryCategory and
SecondaryCategory.

 

[Tom Ellison]

Dear McLitle:

Do some of the Primary Categories have more than one Secondary Category? If
not, what is the source of the duplication.

A DISTINCT query will do what you want:

SELECT DISTINCT PrimaryCategory
FROM YourTable

Make this the RowSource of the combo box.

The solution to this immediate problem does not eliminate the need for good
table design.

Tom Ellison