Option Explicit
'Struct: workbook.worksheet.Cell/Range
'Select workbook:  Workbooks("workbookName")
'NOTE:
'      ThisWorkbook: this vba source code owner workbook
'      ActiveWorkbook: in case mutiple workbook are opened, ActiveWorkbook which is selected(focus)
'                      Worksheet RUN ON ActiveWorkbook
'                      -> ActiveWorkbook.ActiveSheet.Cell/Range
'                      -> BE CAREFUL WHEN OPENED MULTIPLE WORKBOOK AT THE SAME TIME
'Select worksheet: by name Worksheets("worksheetName") or by index  Worksheets(1), Worksheets(2)
'Select current worksheet: ActiveSheet



'Create new blank workbook
Sub workbook_add()
    Dim NewBook As Workbook
    Set NewBook = Workbooks.add
    Debug.Print "NewBook name: " & NewBook.Name
    
    
End Sub





Sub Workbook_open_save()
    Dim filepath As String, filename As String
    filename = "mywb.xlsx"
    filepath = "C:\Users\NinhLD\Downloads\vba\workbook\" & filename
    
 
 
    
    'OPEN WORKBOOK
    Dim targetWorkbook As Workbook
    Set targetWorkbook = Workbooks.Open(filepath)
    
    Debug.Print "ThisWorkbook.Name: " & ThisWorkbook.Name
    Debug.Print "targetWorkbook.Name: " & targetWorkbook.Name
    

  
    'OPENED WORKBOOK INSTANCE
    With targetWorkbook
        'EDIT WORKBOOK
        .Worksheets("Sheet1").Cells(1, 1).Value = "test text"
        
        
        Application.DisplayAlerts = False
        .SaveAs filename:=ThisWorkbook.path & "\copbook.xlsx"   'save mywb.xlsx as other copbook.xlsx
        .Close SaveChanges:=True                                'and CLOSE(SAVE change) mywb.xlsx
        Application.DisplayAlerts = True
        
    End With
    
    'NOTE close without saving
    'Workbooks("BOOK1.XLS").Close SaveChanges:=False
    
End Sub



Sub workbook_active()

    Workbooks("book.xlsx").Activate
    
    ThisWorkbook.Activate
    
End Sub



Sub workbook_listall()
    Debug.Print "Number of opened workbook: " & Workbooks.Count
    
    Dim Item As Workbook
    For Each Item In Workbooks
      Debug.Print "Workbook item: " & Item.Name
    Next
    
End Sub