在下拉列表中有问题 [英] have a problem in dropdownlist

问题描述

此代码正在运行并在gridview中显示数据。

但是现在如果我在组合框中有2或3个值如何选择那个??

 SqlConnection con; 
 con =  new  SqlConnection（connstring）; 
 con.Open（）; 
 
  string  a = DropDownList1.SelectedValue.ToString（）; 
  string  str =   SELECT * FROM [ 'ISB VAS Nodes $'] WHERE HardDisks = + a +  ; 
  //   city是表中的列名 
 SqlCommand cmd; 
 cmd =  new  SqlCommand（str，con）; 
 SqlDataReader dr; 
 dr = cmd.ExecuteReader（）; 
  if （dr.Read（））
 {
 
 TextBox1.Text = dr.GetString（ 0 ）; 
  //  如果city在表的0索引中 
 GridView1.DataSource =博士; 
 GridView1.DataBind（）; 
} 
  else  
 {
 Response.Write（ 城市不存在）; 
 
} 
 dr.Close（）; 
 con.Close（）; 
 

解决方案

'] WHERE HardDisks = + a + ;
// city是表中的列名
SqlCommand cmd;
cmd = new SqlCommand（str，con）;
SqlDataReader dr;
dr = cmd.ExecuteReader（）;
if （dr.Read（））
{

TextBox1.Text = dr.GetString（ 0 ）;
// 如果city在表的0索引中
GridView1.DataSource = dr;
GridView1.DataBind（）;
}
else
{
Response.Write（ 城市不存在）;

}
dr.Close（）;
con.Close（）;

嗨会员7909184334，



根据我的理解，您需要在组合框中选择多个要在搜索查询中使用的值。



如果是这样，那么你可以在一个数组中获得组合框选择的值，并按如下方式设置查询：

  string  str =   SELECT * FROM ['ISB VAS Nodes 

'] WHERE HardDisks IN（ + a [ 0 ]。toString（ ）+ ， + a [ 1 ]。toString（）+ ， + a [ 2 ]。toString（）+ ）;

以上部分显示只有3个选定选项。我们可以使其动态如下：



首先将所有选定的选项放入数组中，我们将其称为 aryOptions

  string   params  =  string  .Empty; 
 
  //  将数组项转换为逗号分隔字符串 
  for （ int  i =  0 ;我<  aryOptions.Length; i ++）
 {
  params  =  params  + aryOptions [i] +  ， ; 
} 
 
  //  删除最后一个逗号 
  if （ params  .Length >   0 ）
 {
  params  =  params  .SubString（ 0 ，parmas.Length  -   1 ）; 
} 
 
  //  使用WHERE IN子句传递值 
  string  str =   SELECT * FROM [ 'ISB增值节点

this code is running and showing the data in gridview.
but now if i have 2 or 3 values in combobox how to pick that??

SqlConnection con;
con = new SqlConnection(connstring);
con.Open();

string a = DropDownList1.SelectedValue.ToString();
string str = "SELECT * FROM ['ISB VAS Nodes$'] WHERE HardDisks=" + a + "";
//city is the column name in table
SqlCommand cmd;
cmd = new SqlCommand(str, con);
SqlDataReader dr;
dr = cmd.ExecuteReader();
if (dr.Read())
{

   TextBox1.Text = dr.GetString(0);
    //if city is in 0 index of table
    GridView1.DataSource = dr;
    GridView1.DataBind();
}
else
{
    Response.Write("City does not exist");

}
dr.Close();
con.Close();

解决方案

'] WHERE HardDisks=" + a + ""; //city is the column name in table SqlCommand cmd; cmd = new SqlCommand(str, con); SqlDataReader dr; dr = cmd.ExecuteReader(); if (dr.Read()) { TextBox1.Text = dr.GetString(0); //if city is in 0 index of table GridView1.DataSource = dr; GridView1.DataBind(); } else { Response.Write("City does not exist"); } dr.Close(); con.Close();

Hi Member 7909184334,

As per my understanding, you need to select multiple values in a combobox which are to be used in the search query.

If so, then you can get the combobox selected values in an array and set the query as follows:

string str = "SELECT * FROM ['ISB VAS Nodes

'] WHERE HardDisks IN (" + a[0].toString() + ", " + a[1].toString() + ", " + a[2].toString() + ")";

The above part shows that there are only 3 selected options. We can make it dynamic as below:

First get all the selected options into an array, lets call it as aryOptions

string params = string.Empty;

// Get the array items into a comma seperated string
for(int i = 0; i < aryOptions.Length; i++)
{  
     params = params + aryOptions[i] + ",";
}

// Remove the last comma
if(params.Length > 0)
{
   params = params.SubString(0, parmas.Length - 1); 
}

// pass the value with WHERE IN clause
string str = "SELECT * FROM ['ISB VAS Nodes

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