How to modify the MS Excel External Data Connection Source/Loction in an C# Visual Studio Application

How to specify a path/location of the MS Access database using Excel interop for the Excel query that queries an MS Access database? Once the application is installed the an Excel spreadsheet is linked to an MS ACCESS database query can no longer locate the database. I would like to use C# code to change the database source. The pertinent code is below.

                Microsoft.Office.Interop.Excel.Application app1 = new Microsoft.Office.Interop.Excel.Application();

                app1.Visible = false;
                app1.DisplayAlerts = false;

                ReportsViewModel vm = (panelAnalysis.DataContext as ReportsViewModel);
                FileInfo fi = vm.ReportFileNamesView.CurrentItem as FileInfo;

                //OleDbConnection thisConnection = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Projects\TrackingMaster\TrackingMasterNew.MDB");
            
                var wb1 = app1.Workbooks.Open(appDir + "\\Projects\\TrackingMaster\\Reports\\Reports_ProjectsbyCohort.xlsx", UpdateLinks: 3);

                wb1.RefreshAll();
                
                foreach (Microsoft.Office.Interop.Excel.Worksheet ws1 in wb1.Worksheets)
                {
               
                   string Label_str1 = " ";
                    string Label_str2 = " ";

                    if (datePicker1_str.ToString("MM/dd/yyyy") != "01/01/1977") { Label_str1 += "    Beginning Report Date: " + datePicker1_str.ToString("MM/dd/yyyy"); }
                    if (datePicker2_str.ToString("MM/dd/yyyy") != "01/01/2050") { Label_str2 += "     Ending Report Date: " + datePicker2_str.ToString("MM/dd/yyyy"); }

                    object misValue = System.Reflection.Missing.Value;
                    ws1.Cells[7, 4] = Label_str1;
                    ws1.Cells[8, 4] = Label_str2;
                    wb1.SaveAs(appDir + "\\Projects\\TrackingMaster\\Reports\\Reports_ProjectsbyCohort.xlsx", Microsoft.Office.Interop.Excel.XlFileFormat.xlWorkbookDefault, Type.Missing, Type.Missing, false, false, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);

                    ws1.ExportAsFixedFormat(XlFixedFormatType.xlTypeXPS, (appDir + "\\Projects\\TrackingMaster\\Reports\\Reports_ProjectsbyCohort.xps"), Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
                    wb1.Close(true, Type.Missing, Type.Missing);
                    app1.Application.Quit();
                    app1.Quit()

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Gerald JonesAsked:
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Ryan ChongBusiness Systems Analyst , ex-Senior Application EngineerCommented:
let's say you already declared your Excel objects:

Microsoft.Office.Interop.Excel.Application app1 = new Microsoft.Office.Interop.Excel.Application();
Microsoft.Office.Interop.Excel.Workbook wb1 = app1.Workbooks.Open(@"D:\yourPath\yourExcel.xlsx", UpdateLinks: 3);

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then to access the connections, try refer to: Microsoft.Office.Interop.Excel.WorkbookConnection object, like:

foreach (Microsoft.Office.Interop.Excel.WorkbookConnection x in wb1.Connections)
            {
                Microsoft.Office.Interop.Excel.OLEDBConnection c = x.OLEDBConnection;
                //try read c.SourceDataFile
            }

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to link to a new Access database, just use:

wb1.Connections.AddFromFile(@"D:\yourPath\yourNewDB.accdb");

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Ryan ChongBusiness Systems Analyst , ex-Senior Application EngineerCommented:
this example was tested working.

have you also tested it out at your end?
Gerald JonesAuthor Commented:
I will test. Do you have time for an online consultation?
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