Import data from a closed workbook (ADO) using VBA in Microsoft Excel

If you want to import a lot of data from a closed workbook you can do this with ADO and the macro below.
If you want to retrieve data from another worksheet than the first worksheet in the closed workbook,
you have to refer to a user defined named range. The macro below can be used like this (in Excel 2000 or later):

GetDataFromClosedWorkbook "C:\FolderName\WorkbookName.xls", "A1:B21", ActiveCell, False
GetDataFromClosedWorkbook "C:\FolderName\WorkbookName.xls", "MyDataRange", Range ("B3"), True 

Sub GetDataFromClosedWorkbook(SourceFile As String, SourceRange As String, _
    TargetRange As Range, IncludeFieldNames As Boolean)
' requires a reference to the Microsoft ActiveX Data Objects library
' if SourceRange is a range reference:
'   this will return data from the first worksheet in SourceFile
' if SourceRange is a defined name reference:
'   this will return data from any worksheet in SourceFile
' SourceRange must include the range headers
'
Dim dbConnection As ADODB.Connection, rs As ADODB.Recordset
Dim dbConnectionString As String
Dim TargetCell As Range, i As Integer
    dbConnectionString = "DRIVER={Microsoft Excel Driver (*.xls)};" & _
        "ReadOnly=1;DBQ=" & SourceFile
    Set dbConnection = New ADODB.Connection
    On Error GoTo InvalidInput
    dbConnection.Open dbConnectionString ' open the database connection
    Set rs = dbConnection.Execute("[" & SourceRange & "]")
    Set TargetCell = TargetRange.Cells(1, 1)
    If IncludeFieldNames Then
        For i = 0 To rs.Fields.Count - 1
            TargetCell.Offset(0, i).Formula = rs.Fields(i).Name
        Next i
        Set TargetCell = TargetCell.Offset(1, 0)
    End If
    TargetCell.CopyFromRecordset rs
    rs.Close
    dbConnection.Close ' close the database connection
    Set TargetCell = Nothing
    Set rs = Nothing
    Set dbConnection = Nothing
    On Error GoTo 0
    Exit Sub
InvalidInput:
    MsgBox "The source file or source range is invalid!", _
        vbExclamation, "Get data from closed workbook"
End Sub

Another method that doesn't use the CopyFromRecordSet-method With the macro below you can perform the import and have better control over the results returned from the RecordSet.

Sub TestReadDataFromWorkbook()
' fills data from a closed workbook in at the active cell
Dim tArray As Variant, r As Long, c As Long
    tArray = ReadDataFromWorkbook("C:\FolderName\SourceWbName.xls", "A1:B21")
    ' without transposing
'    For r = LBound(tArray, 2) To UBound(tArray, 2)
'        For c = LBound(tArray, 1) To UBound(tArray, 1)
'            ActiveCell.Offset(r, c).Formula = tArray(c, r)
'        Next c
'    Next r
    ' with transposing
    tArray = Application.WorksheetFunction.Transpose(tArray)
    For r = LBound(tArray, 1) To UBound(tArray, 1)
        For c = LBound(tArray, 2) To UBound(tArray, 2)
            ActiveCell.Offset(r - 1, c - 1).Formula = tArray(r, c)
        Next c
    Next r
End Sub

Private Function ReadDataFromWorkbook(SourceFile As String, SourceRange As String) As Variant
' requires a reference to the Microsoft ActiveX Data Objects library
' if SourceRange is a range reference:
'   this function can only return data from the first worksheet in SourceFile
' if SourceRange is a defined name reference:
'   this function can return data from any worksheet in SourceFile
' SourceRange must include the range headers
' examples:
' varRecordSetData = ReadDataFromWorkbook("C:\FolderName\SourceWbName.xls", "A1:A21")
' varRecordSetData = ReadDataFromWorkbook("C:\FolderName\SourceWbName.xls", "A1:B21")
' varRecordSetData = ReadDataFromWorkbook("C:\FolderName\SourceWbName.xls", "DefinedRangeName")
Dim dbConnection As ADODB.Connection, rs As ADODB.Recordset
Dim dbConnectionString As String
    dbConnectionString = "DRIVER={Microsoft Excel Driver (*.xls)};ReadOnly=1;DBQ=" & SourceFile
    Set dbConnection = New ADODB.Connection
    On Error GoTo InvalidInput
    dbConnection.Open dbConnectionString ' open the database connection
    Set rs = dbConnection.Execute("[" & SourceRange & "]")
    On Error GoTo 0
    ReadDataFromWorkbook = rs.GetRows ' returns a two dim array with all records in rs
    rs.Close
    dbConnection.Close ' close the database connection
    Set rs = Nothing
    Set dbConnection = Nothing
    On Error GoTo 0
    Exit Function
InvalidInput:
    MsgBox "The source file or source range is invalid!", vbExclamation, "Get data from closed workbook"
    Set rs = Nothing
    Set dbConnection = Nothing
End Function

The macro example assumes that your VBA project has added a reference to the ADO object library.
You can do this from within the VBE by selecting the menu Tools, References and selecting Microsoft
ActiveX Data Objects x.x Object Library.
Use ADO if you can choose between ADO and DAO for data import or export.