如何从数据集中获取值到一个变量?在Web应用程序中 [英] How to get value from dataset to one variable? in web application

问题描述

while循环中有什么错误?

What is an error within while loop?

protected void Page_Load(object sender, EventArgs e)
    {
        string path = "Data Source=192.168.1.14;Initial Catalog=nazer;User ID=sa;Password=admin*123";
        SqlConnection con = new SqlConnection(path);
        con.Open();
        string query = "select MAX(id) from tbl_samp1";
        SqlCommand cmd = new SqlCommand(query, con);        
        SqlDataReader dre=cmd.ExecuteReader();
        while (dre.Read())
        {        
           // int values = int.Parse(dre["id"].ToString());  //pls give any alternate code within while loop.Error occured in this line.
        int values = (int)dre["id"];
        TextBox1.Text = values.ToString();            
        }      
        con.Close();        
    }

推荐答案

看看本文

http://msdn.microsoft.com/en-us/library/haa3afyz (v = vs.90).aspx [

Have A Look At This Article

http://msdn.microsoft.com/en-us/library/haa3afyz(v=vs.90).aspx[^]

Accept This Answer If It Has Helped You

在执行while循环之前，您应验证您是否具有以下有效记录:

Before executing while loop, you should validate whether you have valid records as:

while (dre.Read())
            {

if (dre.HasRows)
       {
           while (dre.Read())
           {

优良作法是使用try..catch块来跟踪异常

It is good practice to trace the exception using try..catch block

先生，

是的，正如Sen所说，您必须始终验证您的dr以检查是否有任何行.

您可以尝试将您的dr转换为toString().

谢谢.

Hi Sir,

Yes, as Sen said you must always validate your dr to check if there is a rows or nothing.

And you can try to convert your dr into toString().

Thank You.

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