Connecting to Oracle 12g with the Instant Client and Excel VBA

Excel References

One rather old application I’ve supported for several years loads data from Excel spreadsheets into a reporting database. These Excel spreadsheets have always been manually updated by several users. However, because the data that the users are entering into these spreadsheets are first being entered into another separate application database, these users have been doing double-entry – a redundant process which can be easily remedied by various means.

Ideally, the solution for this problem would be to extract the data from the application database and load it into the reporting database using an SSIS package. Unfortunately, that would require some redevelopment of the application which loads data into the reporting database, and we (and the customers) have no bandwidth for that. So I came up with a quick workaround that made everyone happy – using a VBA macro to automatically populate the spreadsheets with data when the users open them.

The tricky part here was getting Excel to connect to Oracle with the least amount of work having to be done on the users’ PCs, which are remote from my location.

First of all, since these users don’t require SQL Plus or any development tools for Oracle, the full client software was unnecessary. Also, the Oracle Instant Client could be pushed to the users with Altiris Deployment Solution.

I had the Instant Client software installed on the PCs, then I added the requisite database connection information to the tnsnames.ora file.

Nota bene: In the Instant Client (or at least in our setup, using version 11.2.0.4) the tnsnames file is in
C:\oracle\instantclient_11_2_0_4 rather than in C:\oracle\product\11.2.0.4\client_1\NETWORK\ADMIN as it often would be in the full Oracle client.

The connection in VBA was simple enough, but not immediately obvious – notice that the connection string includes “Microsoft ODBC Driver for Oracle” rather than an Oracle driver; even though this is used, no ODBC connection needs to be set up in the ODBC Data Source Administrator. It is only imperative that the proper entries exist in the tnsnames.ora file, and that the Microsoft ActiveX Data Object Library is installed and referenced in Excel. (Add References by navigating to Tools –> References in the VBA editor in Excel.)

Excel References

In a subroutine, this code was used to connect to the database and pull data.

    Dim SQL_String As String
    Dim dbConnectStr As String
    Dim con As New ADODB.Connection
    Dim recset As New ADODB.Recordset
    Dim strUid As String
    Dim strPwd As String
    Dim strEnv As String
    Dim strDSN As String
    Dim iRow As Integer    
    

    strEnv = "prod"
    strUid = "username"
    strPwd = "password"

    If strEnv = "prod" Then
        strDSN = "(prod database net_service_name* from tnsnames)"
    Else
        strDSN = "(dev database net_service_name* from tnsnames)"
    End If
          
    dbConnectStr = "Driver={Microsoft ODBC for Oracle}; " & _
            "Server=" & strDSN & ";" & _
            "uid=" & strUid & ";pwd=" & strPwd & ";"
       
    con.ConnectionString = dbConnectStr    
    con.Open   
    
    SQL_String = "(insert SQL query here)"
           
    recset.Open SQL_String, con

    iRow = 0 
    Do While Not recset.EOF
         'Have a loop here to go through all the fields
        Sheet1.Range("A" & iRow).Value = recset.Fields("colname") ' colname = Column Name from SQL query
        
        ' &c. ...

        iRow = iRow + 1
        recset.MoveNext
    Loop

    recset.Close
    con.Close

* net_service_name

Oracle Database Error ORA-01013 in Excel VBA After Migrating Application to New Server

VB run-time error ORA-01013

I was testing an old Excel application that I had moved from one server to another and kept getting this error when running it on the new server:

VBA run-time error ORA-01013

The error ORA-01013 (“user requested cancel of current operation”) is commonly a timeout issue. What could be causing a query to timeout on one server, but not another?

In debugging the code, I found that no CommandTimeout property had been set on the Connection object.

Dim cnnRawData As ADODB.Connection
'...    
Set cnnRawData = New ADODB.Connection
cnnRawData.ConnectionString = glbConnectString
cnnRawData.Open
cnnRawData.Execute glbSetCurrentSchema

If it is not explicitly set, this property will default to 30 seconds. However, this did not explain why the query did not timeout on the old server.

The connection to the Oracle Database was being made via ODBC, so I opened the 32-bit ODBC Administrator to see if the connections had been set up differently. This is where I realized what the problem was.

On the old server, the connection configuration looked like this:

ODBC config on old server

And on the new server it looked like this:

ODBC config on new server

See the difference? (Aside from the Description field, that is!)

It’s the “Enable Query Timeout” checkbox in the Application tab. By default, when creating a new connection, it is checked. I unchecked the box and saved the connection, and the error went away.

This is not necessarily the best way to do it, however. I might want some queries to timeout, and not others. In this case the solution would be to set the CommandTimeout property for this particular VBA macro to 0:

Dim cnnRawData As ADODB.Connection
'...    
Set cnnRawData = New ADODB.Connection
cnnRawData.ConnectionString = glbConnectString
cnnRawData.CommandTimeout = 0
cnnRawData.Open
cnnRawData.Execute glbSetCurrentSchema

This would prevent timeouts on this particular connection, but not any others that might be made using the same ODBC connection.

Using Excel VBA to Copy an ADODB Recordset to Multiple Worksheets

In adding functionality to an ancient Excel VBA reporting app for an Oracle database, I decided to set up a temporary worksheet to use as a place to store data before copying it to multiple other worksheets rather than copying directly from the recordset multiple times.

Basically, this VBA procedure takes an ADODB recordset and a Boolean value as parameters. The recordset is the data source, and the Boolean indicates whether or not the data will be copied to a particular worksheet. The temporary worksheet is cleared before the recordset is copied into it, and is cleared again after the data is copied to the other worksheet(s).

Public Sub CopyToSheets(ByRef rs As ADODB.Recordset, ByVal bCopyToSecondSht As Boolean)
    Dim MainSht As Worksheet, TempSht As Worksheet, Rng As Range, c As Range, lastRow As Long, intNextRow As Integer

    Set MainSht = ActiveWorkbook.Worksheets(cMainSht)
    Set TempSht = ActiveWorkbook.Worksheets(cTempData)
     
    TempSht.Cells.Clear
   
    rs.Open
    TempSht.Cells(1, 1).CopyFromRecordset rs
    rs.Close
    
    lastRow = TempSht.Range("A" & Rows.count).End(xlUp).Row
    Set Rng = TempSht.Range("A1:A" & lastRow)
    For Each c In Rng
        intNextRow = NextRowNumber(MainSht)
        c.EntireRow.Copy MainSht.Cells(intNextRow, 1)
        If bCopyToSecondSht Then
            Dim SecondSht As Worksheet
            Set SecondSht = ActiveWorkbook.Worksheets(cSecondSht)
            intNextRow = NextRowNumber(SecondSht)
            c.EntireRow.Copy SecondSht.Cells(intNextRow, 1)
        End If
    Next c
    TempSht.Cells.Clear
End Sub