Bulk copy in Sql using C#

Question

I have a data table .I want to push it to the sql table using Sqlbulkcopy . 

Data table dt=new datatable();some data were loaded
Push this data to sql table.
string connectionstring = @"Data Source";
 using (SqlConnection destinationConnection = new SqlConnection(connectionstring))
  {
 destinationConnection.Open();
 using (SqlBulkCopy bulkCopy =new SqlBulkCopy(destinationConnection.ConnectionString))       {
      bulkCopy.DestinationTableName = "studentmanagement";
      bulkCopy.ColumnMappings.Add("Name", "Name");
      bulkCopy.ColumnMappings.Add("Subjectname", "Subjectname");
      bulkCopy.ColumnMappings.Add("Marks", "Marks");
      bulkCopy.WriteToServer(dt);
   }
   destinationConnection.Close();
 }