Nick,

First, I believe you do have a primary key in your 2-column table, it's the
combination of userid and value. Right? Does it make any sense to have the
same user with the same value more than once in that table?

To address your question. Have a variable named userid on your form, and
make it a drop down list, and populate it with the userid's from your table.
However, edit the SQL to say SELECT DISTINCT userid FROM yourtablename.

Then, have another dropdown list for values. Grab the data from your table
but after selecting the value field hit Filter data, and set the userid value
equal to the value of the field in the first dropdown box. Now you only get
the values associated with that userid.

If you use Windows authtication to link to the database, and you can make
sure the userid matches the domain username. Now you can create a view in the
database like

CREATE VIEW dbo.vUserValues AS
SELECT
   value
FROM
  dbo.yourtablename
WHERE
  userid = SUSER_SNAME()

Now you don't need the userid field. You populate the values dropdown
directly from the view, and you will have a list of values appropriate for
whoever is logged in.

Hope this helps,

Bob