如何使用inset查询进行循环 [英] how to use for loop with inset query

问题描述

int count = Convert.ToInt16(ddlvehicles.SelectedValue);
           for (int i = 2; i <= count; i++)
           {
               cmd.Parameters.Clear();
               cmd.CommandText = "usp_booking_insert";
               cmd.CommandType = CommandType.StoredProcedure;
               cmd.Parameters.AddWithValue("@user_id", ddluname.SelectedValue);
               cmd.Parameters.AddWithValue("@journey_place", txtjplace.Text);
               cmd.Parameters.AddWithValue("@pickup_date", txtpickup_daterri.Text);
               cmd.Parameters.AddWithValue("@pickup_address", txtpickup_address.Text);
               cmd.Parameters.AddWithValue("@return_date", txtreturndate.Text);
               cmd.Parameters.AddWithValue("@return_address", txtreturn_address.Text);
               cmd.Parameters.AddWithValue("@service_id", ddlsname.SelectedValue);
               cmd.Parameters.AddWithValue("@vehicle_id", ddlvehicles.SelectedValue);
               cmd.Parameters.AddWithValue("@vtype_ac_nonac", ddlvtype1.SelectedValue);
               cmd.Parameters.AddWithValue("@vrate_km_day", ddlrate1.SelectedValue);
               cmd.Parameters.AddWithValue("@mode_of_payment", rdbtnpayment.SelectedItem.ToString());
               int vid = Convert.ToInt16(((DropDownList)mvbooking.Views[0].FindControl("ddlvehicles1" + i+1)).SelectedValue);
               string vtype = ((DropDownList)mvbooking.Views[0].FindControl("ddlvtype1" + i+1)).SelectedValue;
               string vrate = ((DropDownList)mvbooking.Views[0].FindControl("ddlvrate1" + i+1)).SelectedValue;

dis是我的插入查询。我想添加车辆，他们被选中。我尝试使用for循环像dis ..但它不工作有一个错误对象引用未设置为对象的实例。在int vid = ...;中line



帮帮我plz

dis is my insert query. bt i want to add vehicle upto they are selected. i tried using for loop like dis.. but it is not working there is an error of "Object reference not set to an instance of an object." in "int vid=...;" line

help me plz

推荐答案

首先，请阅读：系统nullreferenceexception的3个常见原因（对象引用未设置为对象的实例） [ ^ ]



其次，如果你使用：

First of all, read this: 3 common causes of system nullreferenceexception (object reference not set to an instance of an object)[^]

Second, if you use:

int count = Convert.ToInt16(ddlvehicles.SelectedValue);

你怎么能认为下面的代码会正确执行，特别是在时我大于 count ？

how can you excepect that below code will execute correctly, especially when i is bigger then count?

string vtype = ((DropDownList)mvbooking.Views[0].FindControl("ddlvtype1" + i+1)).SelectedValue;

三，你要转换 i + 1 到字符串表达式。尝试使用： Int32.ToString方法 [ ^ ]或 Convert.ToString方法 [ ^ ]。

Third, you want to convert i + 1 to string expression. Try to use: Int32.ToString Method[^] or Convert.ToString method[^].

int count = Convert.ToInt16(ddlvehicles.SelectedValue);
           for (int i = 1; i <= count; i++)
           {
               cmd.Parameters.Clear();
               cmd.CommandText = "usp_booking_insert";
               cmd.CommandType = CommandType.StoredProcedure;
               cmd.Parameters.AddWithValue("@user_id", ddluname.SelectedValue);
               cmd.Parameters.AddWithValue("@journey_place", txtjplace.Text);
               cmd.Parameters.AddWithValue("@pickup_date", txtpickup_daterri.Text);
               cmd.Parameters.AddWithValue("@pickup_address", txtpickup_address.Text);
               cmd.Parameters.AddWithValue("@return_date", txtreturndate.Text);
               cmd.Parameters.AddWithValue("@return_address", txtreturn_address.Text);
               cmd.Parameters.AddWithValue("@service_id", ddlsname.SelectedValue);
               cmd.Parameters.AddWithValue("@mode_of_payment", rdbtnpayment.SelectedItem.ToString());
               int vid = Convert.ToInt16(((DropDownList)mvbooking.Views[0].FindControl("ddlvnameri" + i)).SelectedValue);
               string vtype = ((DropDownList)mvbooking.Views[0].FindControl("ddlvtype" + i)).SelectedValue;
               string vrate = ((DropDownList)mvbooking.Views[0].FindControl("ddlrate" + i)).SelectedValue;
               cmd.Parameters.AddWithValue("@vehicle_id",vid);
               cmd.Parameters.AddWithValue("@vtype_ac_nonac", vtype);
               cmd.Parameters.AddWithValue("@vrate_km_day", vrate);
           }

Thanx所有人为你的合作伙伴操作..但我解决了它

Thanx everyone for your co-operation.. but i solved it

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