dlookup multiple tables and set textbox to result access 2007 - sql

Question

I'll try and break down my problem as best I can and explain what I'm trying to achieve. Firstly, I have three tables:
**RFI** (stands for Request For Information)-
Fields: rfi_id, Customer_id .....
**RFI_project** -
Fields: rfipro_id, project_id, rfi_id *"....." represents other unnecessary fields*
**Customer** -
Fields: Customer_id, company .....
I have an access form with two comboboxes. On the first combobox I select the name of a project at which point the second textbox changes to show those *rfi_id*'s where there is a match with the project name selected.
Now what I'm trying to do is this - When I select an *rfi_id* in the second combobox I want it to display in a textbox on my form the company where there the *rfi_id* value matches the value in the combobox. It's a bit tricky due to the way the tables are joined...here is what I'm essentially trying to display in the textbox field in SQL terms:
SELECT Customer.company, RFI.Customer_id
FROM Customer, RFI
WHERE (((Customer.Customer_id)=[RFI].[Customer_id]) AND ((RFI.rfi_id)=[Forms]![Request for Info Form]![Combo90]))
ORDER BY Customer.company;
In order to do this I have tried the following to no avail. In the after update event of my second combobox I have inserted the following:
companyTB = DLookup("company", "Customer", "Customer_id =" & DLookup("Customer_id", "RFI" And "rfi_id =" & [Forms]![Request for Info Form]![cmbRFI]))
When I change the combobox value I get the error Run-time error '13': Type mismatch. I've tried searching for what I've done wrong but this is a very broad error apparently and I can't find anything similar (or that I understand). I also tried this instead -
companyTB = DLookup("company", "Customer", "Customer_id =" & DLookup("Customer_id", "RFI", "rfi_id =" & cmbRFI))
which gives me the following error - Run-time error '3075': Syntax error(missing operator)in query expression. Anyway, would anybody be kind enough to give me a breakdown of what I need to do to achieve this, or what I'm doing wrong (or maybe a better way to do it?). Forgive me for being to seemingly stupid at this, I've only just begun working with access more in depth in the last 3 weeks or so. Thank you.

Answer 1

Your first DLookUp has incorrect syntax:
companyTB = DLookup("company", "Customer", "Customer_id ="
& DLookup("Customer_id", "RFI" And "rfi_id ="
& [Forms]![Request for Info Form]![cmbRFI]))
I have broken it into three lines to make this easier to see. The second line has And between "RFI" and "rfi_id" when it should have a comma.
companyTB = DLookup("company", "Customer", "Customer_id ="
& DLookup("Customer_id", "RFI", "rfi_id =" & cmbRFI))
The error you are getting on your second combo seems likely to be due to the result returned by cmbRFI. You can check this by filling in an actual rfi_id, rather than the reference to the combo and by setting a text box equal to cmbRFI and see what it is returning. Combo can be difficult because the displayed column and the bound column can be different.
It can be convenient to set up your combobox with several columns, as shown in your query, so the rowsource might be:
SELECT rfi.ID, Customer.company, RFI.Customer_id
FROM Customer
INNER JOIN RFI
ON Customer.Customer_id=RFI.Customer_id
ORDER BY Customer.company;
(or the three tables, joined, if necessary)
Then
Column count = 3
Column widths = 2cm;0;0
Bound column = 1
You can now refer to the second column in your textbox:
= cmbRFI.Column(1)
Columns are numbered from zero.
It is always worth reading up on sql before working with Access:
Fundamental Microsoft Jet SQL for Access 2000
Intermediate Microsoft Jet SQL for Access 2000
Advanced Microsoft Jet SQL for Access 2000

Answer 2

Your last Dlookup statement seems absolutely fine so I'm a little confused as to why it isn't working, you may be able to get round the problem like this though:
Combox2_AfterUpdate (Or whatever the event is called)
Dim rs As Recordset
Set rs = Currentdb.OpenRecordset("SELECT C.Company, R.Customer_ID " & _
"FROM Customer As C, RFI As R " & _
"WHERE C.Customer_ID = R.Customer_ID " & _
"AND R.RFI_ID =" & [Forms]![Request for Info Form]![Combo90] & " " & _
"ORDER BY C.Company")
CompanyTB = rs!Company
rs.Close
Set rs = Nothing
End Sub