如何在以下查询中使用datavaluefield值作为参数值 [英] How do I use datavaluefield value as the parameter value in following query

问题描述

我绑定到dropdownlist，并尝试将datavalue用作以下查询中的参数以绑定到gridview。任何帮助，将不胜感激。代码如下。



我尝试过：

  public   partial   class  ConsolidatedReport：System.Web.UI.Page 
 {
  protected   void  Page_Load（  object  sender，EventArgs e）
 {
 BindCustomersDDL（）; 
} 
 
  private   void  BindCustomersDDL（）
 {
 DataTable dt =  new  DataTable（）; 
 使用（SqlConnection con =  new  SqlConnection（ConfigurationManager.ConnectionStrings [  AMTConnectionString]。ConnectionString））
 {
 con.Open（）; 
 SqlCommand cmd =  new  SqlCommand（ 选择*来自dbo.customer的订单，按2，con）; 
 SqlDataAdapter da =  new  SqlDataAdapter（cmd）; 
 da.Fill（dt）; 
} 
 ddlCustomer.DataSource = dt; 
 ddlCustomer.DataTextField =   cname;  //  您要在下拉列表中显示的内容 
 ddlCustomer.DataValueField =   customerid; 
 ddlCustomer.DataBind（）; 
 
 
} 
 
 受保护  void  btnExecute_Click（ object  sender，EventArgs e）
 {
 BindBacteriaGrid（）; 
 
} 
 
  private   void  BindBacteriaGrid（） 
 {
 DataTable dt =  new  DataTable（）; 
  try  
 {
 SqlConnection con =  new  SqlConnection（ConfigurationManager。 ConnectionStrings [  AMTConnectionString]。ConnectionString）; 
 SqlDataAdapter adp =  new  SqlDataAdapter（  SELECT [CustomerID]，WellID，SRB_RISK，来自[AMT]的APB_RISK。[dbo] .bacteria其中customerid = @cust order by 1，con）; 
 adp.SelectCommand.Parameters.AddWithValue（  @ cust，ddlCustomer.Text）; 
 adp.Fill（dt）; 
 
  if （dt.Rows.Count >   0 ）
 {
 BacteriaGridview.DataSource = dt; 
 BacteriaGridview.DataBind（）; 
} 
  else  
 {
 BacteriaGridview.DataSource =  null ; 
 BacteriaGridview.DataBind（）; 
} 
} 
  catch （例外情况）
 {
 Response.Write（ 错误发生： + ex.ToString（））; 
} 
 最后 
 {
 dt.Clear（）; 
 dt.Dispose（）; 
} 
} 
 

解决方案

Page.IsPostback 缺失

 受保护  void  Page_Load（ object  sender，EventArgs e）
 {
  if （Page .IsPostBack） return ; 
 BindCustomersDDL（）; 
 
} 

用于阅读下拉选项，使用

  var  text = ddlCustomer.SelectedItem.Text; 
  var   value  = ddlCustomer.SelectedItem.Value; 

I bind to dropdownlist, and am trying to use the datavalue as the parameter in my following query to bind to gridview. any help would be appreciated. Code below.

What I have tried:

public partial class ConsolidatedReport : System.Web.UI.Page
   {
       protected void Page_Load(object sender, EventArgs e)
       {
           BindCustomersDDL();
       }

       private void BindCustomersDDL()
       {
           DataTable dt = new DataTable();
           using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["AMTConnectionString"].ConnectionString))
           {
               con.Open();
               SqlCommand cmd = new SqlCommand("Select * from dbo.customer order by 2", con);
               SqlDataAdapter da = new SqlDataAdapter(cmd);
               da.Fill(dt);
           }
           ddlCustomer.DataSource = dt;
           ddlCustomer.DataTextField = "cname";//Which you want to display inthe dropdownlist
           ddlCustomer.DataValueField = "customerid";
           ddlCustomer.DataBind();


       }

       protected void btnExecute_Click(object sender, EventArgs e)
       {
           BindBacteriaGrid();

       }

       private void BindBacteriaGrid()
       {
           DataTable dt = new DataTable();
           try
           {
               SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["AMTConnectionString"].ConnectionString);
               SqlDataAdapter adp = new SqlDataAdapter("SELECT [CustomerID], WellID, SRB_RISK, APB_RISK  from [AMT].[dbo].bacteria where customerid = @cust order by 1", con);
               adp.SelectCommand.Parameters.AddWithValue("@cust", ddlCustomer.Text);
               adp.Fill(dt);

               if (dt.Rows.Count > 0)
               {
                   BacteriaGridview.DataSource = dt;
                   BacteriaGridview.DataBind();
               }
               else
               {
                   BacteriaGridview.DataSource = null;
                   BacteriaGridview.DataBind();
               }
           }
           catch (Exception ex)
           {
               Response.Write("Error Occured: " + ex.ToString());
           }
           finally
           {
               dt.Clear();
               dt.Dispose();
           }
       }

解决方案

Page.IsPostback is missing

protected void Page_Load(object sender, EventArgs e)
      {
          if (Page.IsPostBack) return;
          BindCustomersDDL();

      }

for reading the dropdown selected item, use

var text = ddlCustomer.SelectedItem.Text;
var value = ddlCustomer.SelectedItem.Value;

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