如何导出到.csv文件

Question

I have a basic VB.net program that runs a query against a database to extract customer information to send coupons. What I'd like to do, is when I push a command button to return the results and create a .csv file on the computer that runs the program... Right now, I have a program that runs the query, and dumps the results to report viewer, however I cannot export to .csv, and there are too many records to show on the report viewer...

Here is my code so far... I assume I need to build the layout in XML form?

    Dim str As New StringBuilder

            For Each dr As DataRow In Me.DataDeliveryServiceDataSet.Invoice_Tb

                For Each field As Object In dr.ItemArray

                    str.Append(field.ToString & ",")

                Next

                str.Replace(",", vbNewLine, str.Length - 1, 1)

            Next



            Try

                My.Computer.FileSystem.WriteAllText("C:\temp\testcsv.csv", str.ToString, False)

            Catch ex As Exception

                MessageBox.Show("Write Error")
End Try
End Sub

Answer 1

You could replace the inner loop with this short version using LinQ

Dim str As New StringBuilder 
For Each dr As DataRow In Me.DataDeliveryServiceDataSet.Invoice_Tb 
    str.AppendLine(string.Join(",", _ 
             dr.ItemArray.Select(Function(o) if(o = DBNull.Value,"",o.ToString()))))
Next 

of course, if you need to export in XML format is enough to use the WriteXml method of the datatable

Me.DataDeliveryServiceDataSet.Invoice_Tb.WriteXml("C:\temp\testcsv.csv")