Question : ADO Update Multiple Access Databases / Error with Null Date Value

Hi All

Have a problem with updating a synchronised Access DB, when a Date is unchecked from a Date picker in a VB6 Windows Forms Application. Also this process works fine with all other Field Updates except where Dates are Empty.

When a NULL Value is passed in (Date changed from Some Date to Nothing) the rs.Update does nothing to the value in the second DB.

If I attempt to trap the value and update it to an Empty string or other I get the following error.
ADODB.Field
Description: Current Recordset does not support updating. This may be a limitation of the provider, or of the selected locktype.

And if I declare a variable to catch the adoDB.field Type, I get
Description: Invalid use of Null

This is Old Code from a previous developer and to be honest I am struggling to understand the best way to fix it.

I have attached the code below and added comments to the relevant areas. The problem occurs specifically with field.type (7) i.e. 'adDate'.

By the way the field Definition in the Access Table is set to "Required = No". for this EndDate Field.

My gut feeling is I need to revert to some form of "Update" SQL Statement or to even delete the row from the External DB and to just reinsert the record if a change is made.

I have spent many hours trying to track down the best way to deal with this so any help would be appreciated.

Cheers FLOG51

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:
28:
29:
30:
31:
32:
33:
34:
35:
36:
37:
38:
39:
40:
41:
42:
43:
44:
45:
46:
47:
48:
49:
50:



Private Function updateExternalDB(ByVal auditId As String, ByVal externalDB As adoUtil, ByVal tablename As String, ByVal key As String, ByVal oldKey As String) As String
    On Error Resume Next
    Dim errorStr As String
    Dim searchKey As String

	Dim parentRS As Object
	' gDBUtility is declared as Global and .getParentRSA routine Successfully retrieves field Data from Parent Database Table
	' This is carried out after the Parent Table has Successfully been updated with Empty Values for relevant dates.
	Set parentRS = gDBUtility.getParentRSA("select " & gDBUtility.getMyTableExportFields & " from myTable where cardnumber = " & key)

	If Not parentRS Is Nothing Then
	  If parentRS.EOF = False Then
	    If errorStr = "" Then
	      Dim externalparentRS As Object					
	      Set externalparentRS = externalDB.getParentRSA("select * from " & tablename & " where cardnumber = " & key, True)
	        If externalparentRS Is Nothing Then
		      Set externalparentRS = externalDB.getParentRSA(tablename, True, , True)
		      externalparentRS.addNew
	        Else
		      If externalparentRS.EOF Then
			    externalparentRS.addNew
		      End If
	        End If
	
	          Dim f As adoDB.field
	          Dim fieldname As String
	          For Each f In parentRS.fields
		        fieldname = f.name				
		        If Not IsNull(parentRS.fields(fieldname)) Then
			      If parentRS.fields(fieldname) <> "" Then
			        ' This line below is where the NULL date value is passed and never inputs at externalparentRS.Update 
				     externalparentRS.fields(fieldname) = parentRS.fields(fieldname)
				    If err.Number <> 0 Then
					  'Debug.Print "Failed: " & err.description
				    End If
			      End If
		        End If
	          Next
	          externalparentRS.Update
	          If err.Number <> 0 Then
		        updateExternalDB = err.description
	          End If
	    Else
	      updateExternalDB = errorStr
	    End If
	  End If
	End If
	parentRS.Close
	Set parentRS = Nothing
End Function

Answer : ADO Update Multiple Access Databases / Error with Null Date Value

       For Each f In parentRS.fields 'iterate through each field in the parentRS recordset
              fieldname = f.name             'assign the name of the current field to a string variable

'here's where I'm getting confused

              If Not IsNull(parentRS.fields(fieldname)) Then 'only proceed if the value of the current field is NOT NULL
                   If parentRS.fields(fieldname) <> "" Then 'only proceed if the value of the current field is NOT AN EMPTY STRING

'how are we getting here if a Null value is being passed???? The conditionals above should prevent this

                   ' This line below is where the NULL date value is passed and never inputs at externalRS.Update
                          externalRS.fields(fieldname) = parentRS.fields(fieldname) 'if we get here then set the value of the externalRS recordset field to the same value as the parentRS field
                          If err.Number <> 0 Then
                               'Debug.Print "Failed: " & err.description
                          End If
                   End If
              End If
       Next
       externalRS.Update 'update the recordset