列表框选定的项目 [英] Listbox selected items

问题描述

我正在开发winforms应用程序，



listbox是多选列表框。



填充包含数据源的列表框，具体取决于列表框中的选定值，

i需要从数据库中获取数据，



如何解决它。

< pre lang =   c＃ >  使用（MySqlConnection con =  new  MySqlConnection（ConnectionString））
 {
  string  query =  从客户选择不同的area_code; 
 con.Open（）; 
 MySqlDataAdapter da =  new  MySqlDataAdapter（query，con）; 
 DataTable dt =  new  DataTable（）; 
 da.Fill（dt）; 
 listBox1.DataSource = dt; 
 listBox1.DisplayMember =   area_code; 
 
} 

列表框显示正常，如下：11

33

44



当我选择11,33



i需要一个查询来从数据库中选择数据。



我正在使用：

< pre lang =   c＃ >   foreach （对象项目  listBox1.Items ）
 {
 text + = item.ToString（）+  ; 
} 
 
 area = text; 

和查询是：

query1 =select customer_id，name，area，mobile_number，package_name，package_type，activation_date，status，monthly_amount，lastpaid_date，lastpaid_amount，nextpay_date，totalamount_paid，totaldue_amount，total_charges from customer where area_code =+ area +;

解决方案

首先，您应该像这样构建区域临时字符串：

  string  area =  string  .Empty; 
  foreach （对象项目  listBox1.Items）
 {
  if （area.Length >  < span class =code-digit> 0 ）area + =  ，; 
 area + = item.ToString（）; 
} 

然后使用区域字符串构建您的查询：

 query1 =   select customer_id，name，area，mobile_number，package_name，package_type，activation_date，status，monthly_amount ，lastpaid_date，lastpaid_amount，nextpay_date，totalamount_paid，totaldue_amount，total_charges from customer where area_code in（ + area +   ）; 

Hi,

am developing winforms application,

listbox is multiselection listbox.

am filling listbox with datasource, depending on selected values from listbox,
i need to get data from database,

how to solve it.

<pre lang="c#"> using (MySqlConnection con = new MySqlConnection(ConnectionString))
            {
                string query = "select distinct area_code from customer";
                con.Open();
                MySqlDataAdapter da = new MySqlDataAdapter(query,con);
                DataTable dt = new DataTable();
                da.Fill(dt);
                listBox1.DataSource = dt;
                listBox1.DisplayMember = "area_code";
            
            }

listbox is displaying fine as ex:11
33
44

when i select 11, 33

i need a query to select data from database.

am using:

<pre lang="c#"> foreach (Object item in listBox1.Items)
            {
                text += item.ToString() + " ";
            }

            area = text;

and query is:
query1 = "select customer_id,name,area,mobile_number,package_name,package_type,activation_date,status,monthly_amount,lastpaid_date,lastpaid_amount,nextpay_date,totalamount_paid,totaldue_amount,total_charges from customer where area_code="+area+" ";

解决方案

First you should build your area temp string like this:

string area = string.Empty;
foreach (Object item in listBox1.Items)
{
 if(area.Length > 0) area += ", ";
 area += item.ToString();
}

Then to use the area string to build your query:

query1 = "select customer_id,name,area,mobile_number,package_name,package_type,activation_date,status,monthly_amount,lastpaid_date,lastpaid_amount,nextpay_date,totalamount_paid,totaldue_amount,total_charges from customer where area_code in ("+area+")";

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