Use of sql Bulk copy

 public Int16 ImportIUploadQuestionnaire(OM_UploadQuestionnaire objUploadQuestionnaire)
        {
           
            using (SqlConnection cn = OceanManager.SQLHelper.GetSQLConnection(Databases.AuditSystem))
            {               
                using (SqlBulkCopy copy = new SqlBulkCopy(cn))
                {

                    copy.ColumnMappings.Add("UserID", "UserID");
                    copy.ColumnMappings.Add("CheckList", "CheckList");
                    copy.ColumnMappings.Add("Question", "Question");
                    copy.ColumnMappings.Add("Guidance", "Guidance");
                    copy.ColumnMappings.Add("Priority", "Priority");
                    copy.ColumnMappings.Add("Rank", "Rank");
                    copy.ColumnMappings.Add("QuestionType", "QuestionType");
                    copy.ColumnMappings.Add("Task", "Task");
                    copy.ColumnMappings.Add("AuditType", "AuditType");
                    copy.ColumnMappings.Add("AuditName", "AuditName");  
                    copy.DestinationTableName = TABLE_QuestionnaireUpload;
                    copy.WriteToServer(objUploadQuestionnaire.ImportDatTable);

                 

                }
                cn.Close();
                cn.Dispose();
              
            }

            return 1;

        }