Question

i need to create a lookup table in Access, where all the abbreviations are related to a value, and if the abbreviation (in the main table) is null, then i want to show “Unknown”

i got the values working, but i can’t seem to get the nulls to show up.

my lookup table looks like this:

REQUEST     REQUEST_TEXT
------------------------
A           Approve
D           Disapprove
NULL        N/A

but when i do a count by request, it only shows me values for A and D, all though i know there are some blanks in there as well.

what am i doing wrong?

Answer 1

This should be easier if you change tblLookup.

REQUEST     REQUEST_TEXT
------------------------
A           Approve
D           Disapprove
U           Unknown

Then, in tblMain, change the REQUEST field to Required = True and Default Value = “U”. When new records are added, they will have U for REQUEST unless the user changes it to A or D.

Then a query which JOINs the 2 tables on REQUEST should get you what I think you want.

SELECT m.REQUEST, l.REQUEST_TEXT
FROM tblMain AS m
    INNER JOIN tblLookup AS l
    ON l.REQUEST = m.REQUEST;

You should also create a relationship between the 2 tables, and select the option to enforce referential integrity in order to prevent the users from adding a spurious value such as “X” for REQUEST.

Edit:
If changing tblMain structure is off the table, and if you’re doing this from within an Access session, you can use the Nz() function on a LEFT JOIN.

SELECT m.REQUEST, Nz(l.REQUEST_TEXT, "Unknown")
FROM tblMain AS m
    LEFT JOIN tblLookup AS l
    ON l.REQUEST = m.REQUEST;

If you’re doing this from outside an Access session, like from ASP, the Nz() function will not be available. So you can substitute an IIf() expression for Nz().

SELECT m.REQUEST, IIf(l.REQUEST_TEXT Is Null, "Unknown", l.REQUEST_TEXT)
FROM tblMain AS m
    LEFT JOIN tblLookup AS l
    ON l.REQUEST = m.REQUEST;

Edit2: You can’t directly JOIN with Null values. However with the “Unknown” row I suggested for tblLookup, you could use a JOIN which includes Nz for tblMain.REQUEST

SELECT m.id, m.request, l.request_text
FROM tblMain AS m
    INNER JOIN tblLookup AS l
    ON Nz(m.request,"U") = l.request;

If you want to leave tblLookup REQUEST as Null for REQUEST_TEXT = Unknown, I suppose you could use Nz on both sides of the JOIN expression. However, this whole idea of joining Nulls makes me cringe. I would fix the tables instead.