批量插入表数据最快效率（DataTabel到表）

 public bool SqlBulkCopyByDatatable(DataTable dt,ref string emsg)
        {
            try
            {
                SqlBulkCopy sqlbulkcopy = new SqlBulkCopy(SqlHelper.connStr, SqlBulkCopyOptions.UseInternalTransaction);
                sqlbulkcopy.DestinationTableName = dt.TableName;
                foreach (DataColumn dc in dt.Columns)
                {
                    sqlbulkcopy.ColumnMappings.Add(dc.ColumnName, dc.ColumnName);
                }
                sqlbulkcopy.WriteToServer(dt);
                return true;
            }
            catch (Exception ex)
            {
                emsg = ex.ToString();
                return false;
            }
        }