Crosschecking account number between two access tables when using forms - forms

Question

I am using a form to enter new data into the table: tblMonthlySummary. I am entering Account Number, Currency, and Closing Local Balance.
When I enter the account number into table tblMonthlySummary, I would like Access, either through a macro or VBA, to crosscheck the table tblStaticBankDetails for the account number that would be added to tblMonthlySummary.
If the account number does not exist in tblStaticBankDetails, I would like VBA or a macro to return a Windows dialog box that says, "Invalid account number".
Here is the current code I have in VBA for my Add Entry to Table Button, Clear Fields, and Close Form. These buttons are on a form labeled: frmMonthlyManualUpdate.
Add Data Code
Private Sub cmdAdd_Click()
'add data to table
CurrentDb.Execute "INSERT INTO tblMonthlySummary([Account Number], [Currency], [Closing Balance]) " & _
" VALUES('" & Me.txtAccountNumber & "','" & Me.cboGender2 & "', '" & Me.txtClosingBalance & "')"
'clear form
cmdClear_Click
'refresh data in list on form
frmMonthlySummarySub.Form.Requery
'confirmation of end
MsgBox "Account number and balance successfully recorded."
End Sub
Me.cbogender2 is my currency blank.
Clear Fields Code
Private Sub cmdClear_Click()
Me.txtAccountNumber = ""
Me.cboGender2 = ""
Me.txtClosingBalance = ""
'focus on TxtAccountNumber
Me.txtAccountNumber.SetFocus
End Sub
Close Form Code
Private Sub cmdClose_Click()
DoCmd.Close
End Sub

Answer 1

Using a combo box is the way to go.
You can set it's properties to only allow values that are on it's list to be entered into the field. Users can either choose a value from it's list OR type the account manually. It won't let a value be entered that is not on the list.
How many accounts might have their summary row missing?
If it's only a small number you might want to consider:
Using SQL to insert the account numbers that are not in tblMonthlySummary that are in tblStaticBankDetails.
Then the user can see which ones are missing and find out what the values should be. (ie filter to form to view account with missing details)
It is strange that you are using a button to execute and insert statement. It is more common for an Access form to be based on an updatable record source (like you list) and for the user to simply click the "new record" button to insert a row.
PS. I would expect referential integrity to be set up between these two tables to stop any incorrect values being entered for account number as well.
Harvey