打开 A（新）工作簿，即使它已经打开

如果要访问已打开的工作簿，则从 Workbooks 集合中获取分配非常简单：

dim myWB as Workbook
Set myWB = Workbooks("UsuallyFullPathnameOfWorkbook.xlsx")

如果要创建新工作簿，请使用 Workbooks 集合对象来创建新条目。

Dim myNewWB as Workbook
Set myNewWB = Workbooks.Add

有时你可能不会或（或关心）你所需的工作簿是否已打开，或者可能不存在。示例函数显示如何始终返回有效的工作簿对象。

Option Explicit
Function GetWorkbook(ByVal wbFilename As String) As Workbook
    '--- returns a workbook object for the given filename, including checks
    '    for when the workbook is already open, exists but not open, or
    '    does not yet exist (and must be created)
    '    ***  wbFilename must be a fully specified pathname
    Dim folderFile As String
    Dim returnedWB As Workbook
    
    '--- check if the file exists in the directory location
    folderFile = File(wbFilename)
    If folderFile = "" Then
        '--- the workbook doesn't exist, so create it
        Dim pos1 As Integer
        Dim fileExt As String
        Dim fileFormatNum As Long
        '--- in order to save the workbook correctly, we need to infer which workbook
        '    type the user intended from the file extension
        pos1 = InStrRev(sFullName, ".", , vbTextCompare)
        fileExt = Right(sFullName, Len(sFullName) - pos1)
        Select Case fileExt
            Case "xlsx"
                fileFormatNum = 51
            Case "xlsm"
                fileFormatNum = 52
            Case "xls"
                fileFormatNum = 56
            Case "xlsb"
                fileFormatNum = 50
            Case Else
                Err.Raise vbObjectError + 1000, "GetWorkbook function", _
                         "The file type you've requested (file extension) is not recognized. " & _
                         "Please use a known extension: xlsx, xlsm, xls, or xlsb."
        End Select
        Set returnedWB = Workbooks.Add
        Application.DisplayAlerts = False
        returnedWB.SaveAs filename:=wbFilename, FileFormat:=fileFormatNum
        Application.DisplayAlerts = True
        Set GetWorkbook = returnedWB
    Else
        '--- the workbook exists in the directory, so check to see if
        '    it's already open or not
        On Error Resume Next
        Set returnedWB = Workbooks(sFile)
        If returnedWB Is Nothing Then
            Set returnedWB = Workbooks.Open(sFullName)
        End If
    End If
End Function