我从数据库中检索数据时遇到错误 [英] i am getting error while retrieving data from database

问题描述

 protected void Submitbtn_Click（object sender，EventArgs e）
 {
 
 
 
 string connection_string = @Provider = Microsoft.Jet .OLEDB.4.0;数据源= C：\ HILProject\project4 \ App_Data \ adminmin.mdb; 
使用（OleDbConnection cn = new OleDbConnection（connection_string））
 {
 cn.Open（）; 
 
 
 String str =select * from BasicDtl_tbl where UserName =+ usertxt.Text +; 
 OleDbCommand cmd = new OleDbCommand（str，cn）; 
 // cmd.Connection = cn; 
 OleDbDataAdapter ad = new OleDbDataAdapter（cmd）; 
 System.Data.DataSet ds = new System.Data.DataSet（）; 
 ad.Fill（ds）; 
 
 Nattxt.Text = ds.Tables [0] .Rows [0] .ItemArray [2] .ToString（）; 
 apldposttxt.Text = ds.Tables [0] .Rows [0] .ItemArray [3] .ToString（）; 
 cn.Close（）; 
} 
} 

显示错误

在执行当前Web请求期间生成了未处理的异常。可以使用下面的异常堆栈跟踪来识别有关异常的起源和位置的信息。

一个页面只能有一个服务器端的Form标记。

解决方案

一个页面只能有一个服务器端表单标签

在查询中添加适当的引号

  String  str =  从BasicDtl_tbl中选择*，其中UserName =' + usertxt.Text +  '; 

您的页面有两个表单标签， runat =server或您的母公司和内容页面都有的表单标签runat =server所以删除额外的表格标签.. :)）

protected void Submitbtn_Click(object sender, EventArgs e)
    {



        string connection_string = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\HILProject\project4\App_Data\adminlog.mdb";
        using (OleDbConnection cn = new OleDbConnection(connection_string))
        {
            cn.Open();
           
           
            String str = "select * from BasicDtl_tbl where UserName=" + usertxt.Text + "";
             OleDbCommand cmd = new OleDbCommand(str,cn);
           // cmd.Connection = cn;
           OleDbDataAdapter ad = new OleDbDataAdapter(cmd);
          System.Data.DataSet  ds = new System.Data.DataSet();
           ad.Fill(ds);

           Nattxt.Text = ds.Tables[0].Rows[0].ItemArray[2].ToString();
           apldposttxt.Text = ds.Tables[0].Rows[0].ItemArray[3].ToString();
           cn.Close();
        }
    }

error shown is
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
A page can have only one server-side Form tag.

解决方案

A page can have only one server-side Form tag

add appropriate quotes in the query

String str = "select * from BasicDtl_tbl where UserName='" + usertxt.Text + "'";

Either your page has two form tag with runat="server" or your masterpage and contentpage both has form tag with runat="server" so remove extra form tag.. :)

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