dapper 写查询sql 时，多条件参数操作方法

var args = new DynamicParameters(new {});


   if (obj.orderId != null)
   {
        sb.Append(" AND OrderId = @OrderId");
        args.Add("OrderId", obj.orderId);
    }

    if (obj.clientName != null)
   {
        sb.Append("  AND b.Name = @ClientName");
        args.Add("ClientName", obj.clientName); 
    }

conn.Query<TModel>(sql, args );