MS Access: How to bypass/suppress an error? - ms-access

Question

I'm executing a query like this
select field from table;
In that query, there is a loop running on many tables. So, if the field is not present in a table I get a
Runtime Error 3061
How can I by pass this error such as that on this error flow should go to another point?
This is the code I have recently after going through this forum.
Option Explicit
Private Sub UpdateNulls()
Dim rs2 As DAO.Recordset
Dim tdf As DAO.TableDef
Dim db As Database
Dim varii As Variant, strField As String
Dim strsql As String, strsql2 As String, strsql3 As String
Dim astrFields As Variant
Dim intIx As Integer
Dim field As Variant
Dim astrvalidcodes As Variant
Dim found As Boolean
Dim v As Variant
Open "C:\Documents and Settings\Desktop\testfile.txt" For Input As #1
varii = ""
Do While Not EOF(1)
Line Input #1, strField
varii = varii & "," & strField
Loop
Close #1
astrFields = Split(varii, ",") 'Element 0 empty
For intIx = 1 To UBound(astrFields)
'Function ListFieldDescriptions()
Dim cn As New ADODB.Connection, cn2 As New ADODB.Connection
Dim rs As ADODB.Recordset, rs3 As ADODB.Recordset
Dim connString As String
Dim SelectFieldName
Set cn = CurrentProject.Connection
SelectFieldName = astrFields(intIx)
Set rs = cn.OpenSchema(adSchemaColumns, Array(Empty, Empty, Empty, SelectFieldName))
'Show the tables that have been selected '
While Not rs.EOF
'Exclude MS system tables '
If Left(rs!Table_Name, 4) <> "MSys" Then
strsql = "Select t.* From [" & rs!Table_Name & "] t Inner Join 01UMWELT On t.fall = [01UMWELT].fall Where [01UMWELT].Status = 4"
End If
Set rs3 = CurrentDb.OpenRecordset(strsql)
'End Function
strsql2 = "SELECT label.validcode FROM variablen s INNER JOIN label ON s.id=label.variablenid WHERE varname='" & astrFields(intIx) & "'"
Set db = OpenDatabase("C:\Documents and Settings\Desktop\Codebook.mdb")
Set rs2 = db.OpenRecordset(strsql2)
With rs2
.MoveLast
.MoveFirst
astrvalidcodes = rs2.GetRows(.RecordCount)
.Close '
End With
With rs3
.MoveFirst
While Not rs3.EOF
found = False
For Each v In astrvalidcodes
If v = .Fields(0) Then
found = True
Debug.Print .Fields(0)
Debug.Print .Fields(1)
Exit For
End If
Next
If Not found Then
msgbox "xxxxxxxxxxxxxxxx"
End If
End If
.MoveNext
Wend
End With
On Error GoTo 0 'End of special handling
Wend
Next intIx
End Sub
I'm getting a
Type Mismatch Runtime Error
in Set rs3 = CurrentDb.OpenRecordset(strsql)
I guess I'm mixing up ado and dao but I'm not certainly sure where it is.

Answer 1

Use the On Error statement that VBA supplies:
Sub TableTest
On Error Goto TableTest_Error
' ...code that can fail... '
Exit Sub
:TableTest_Error
If Err.Number = 3061 Then
Err.Clear()
DoSomething()
Else
MsgBox Err.Description ' or whatever you find appropriate '
End If
End Sub
Alternatively, you can switch off automatic error handling (e.g. breaking execution and displaying an error message) on a line-by-line basis:
Sub TableTest
' ... fail-safe code ... '
On Error Resume Next
' ...code that can fail... '
If Err.Number = 3061 Then
Err.Clear()
DoSomething()
Else
MsgBox Err.Description
End If
On Error Goto 0
' ...mode fail-safe code... '
End Sub
There are these statements available:
On Error Resume Next switches off VBA-integrated error handling (message box etc.) completely, execution simply resumes on the next line. Be sure to check for an error very early after you've used that, as a dangling error can disrupt the normal execution flow. Clear the error as soon as you caught it to prevent that.
On Error Goto <Jump Label> resumes execution at a given label, primarily used for per-function error handlers that catch all sorts of errors.
On Error Goto <Line Number> resumes at a given line number. Stay away from that, it's not useful, even dangerous.
On Error Goto 0 it's close cousin. Reinstates the VBA integrated error management (message box etc.)
EDIT
From the edited qestion, this is my proposal to solve your problem.
For Each FieldName In FieldNames ' assuming you have some looping construct here '
strsql3 = "SELECT " & FieldName & " FROM table"
On Error Resume Next
Set rs3 = CurrentDb.OpenRecordset(strsql3)
If Err.Number = 3061 Then
' Do nothing. We dont care about this error '
Err.Clear
Else
MsgBox "Uncaught error number " & Err.Number & " (" & Err.Description & ")"
Err.Clear
End If
On Error GoTo 0
Next FieldName
Be sure to clear the error in any case before you go on with a loop in the same Sub or Function. As I said, a dangling error causes code flow to become unexpected!

Answer 2

Rather than trapping the error, why not use the TableDefs to check for the field or use a mixture of ADO and DAO? ADO Schemas can provide a list of tables that contain the required field:
Function ListTablesContainingField()
Dim cn As New ADODB.Connection, cn2 As New ADODB.Connection
Dim rs As ADODB.Recordset, rs2 As ADODB.Recordset
Dim connString As String
Dim SelectFieldName
Set cn = CurrentProject.Connection
SelectFieldName = "Fall" 'For tksy '
'Get names of all tables that have a column called 'ID' '
Set rs = cn.OpenSchema(adSchemaColumns, _
Array(Empty, Empty, Empty, SelectFieldName))
'Show the tables that have been selected '
While Not rs.EOF
'Exclude MS system tables '
If Left(rs!Table_Name, 4) <> "MSys" Then
' Edit for tksy, who is using more than one forum '
If tdf.Name = "01UMWELT" Then
strSQL = "Select * From 01UMWELT Where Status = 5"
Else
strSQL = "Select a.* From [" & rs!Table_Name _
& "] a Inner Join 01UMWELT On a.fall = 01UMWELT.fall " _
& "Where 01UMWELT.Status = 5"
End If
Set rs2 = CurrentDb.OpenRecordset(strSQL)
Do While Not rs2.EOF
For i = 0 To rs2.Fields.Count - 1
If IsNull(rs2.Fields(i)) Then
rs2.Edit
rs2.Fields(i) = 111111
rs2.Update
End If
Next
rs2.MoveNext
Loop
End If
rs.MoveNext
Wend
rs.Close
Set cn = Nothing
End Function

Answer 3

Try this:
On Error Resume Next ' If an error occurs, move to next statement.
...statement that tries the select...
If (Err <> 0) Then
...act on error, or simply ignore if necessary...
End If
On Error Goto 0 ' Reset error handling to previous state.