C#从下拉选项填充网格视图

本文关键字：填充 网格 视图 选项 | 更新日期: 2023-09-27 17:58:30

我尝试了所有方法，但不知道如何用下拉选择填充网格视图。我已经检查了下拉列表的值，它是正确的，网格视图将显示所有项目，但不显示我想要的项目。我正在使用一个web表单。下面是我的代码。

protected void Page_Load(object sender, EventArgs e)
        {
            Populate();
        }
        protected void btnDisplay_Click(object sender, EventArgs e)
        {
            SqlConnection myConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString);
            myConnection.Open();
            try
            {
                SqlDataReader reader = null;
                string serverIP = drpChoose.SelectedItem.Value.ToString();
                SqlCommand cmd = new SqlCommand("SELECT * from ScheduledTasks WHERE ServerIP = " + serverIP, myConnection);
                reader = cmd.ExecuteReader();
                while (reader.Read())
                {
                    GridView1.DataSource = reader;
                    GridView1.DataBind();
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            myConnection.Close();
        }
        public void Populate()
        {
            SqlConnection myConnection1 = new SqlConnection(ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString);
            myConnection1.Open();
            SqlCommand cmd1 = new SqlCommand("SELECT ServerIP FROM Servers", myConnection1);
            SqlDataReader dropReader;
            dropReader = cmd1.ExecuteReader();
            drpChoose.DataSource = dropReader;
            drpChoose.DataTextField = "ServerIP";
            drpChoose.DataValueField = "ServerIP";
            drpChoose.DataBind();
        }
    }

如有任何帮助，我们将不胜感激。

C#从下拉选项填充网格视图

您还应该应用sql参数化。它将有助于防止SQL注入攻击。您的代码当前易受攻击。

http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlparametercollection.addwithvalue.aspx

您不需要在每次发布后重新绑定下拉列表，否则您将丢失所选项目。尝试以下操作：

protected void Page_Load(object sender, EventArgs e)
        {
        if(!Page.IsPostBack)
            {
            Populate();                
            }
    }
    protected void btnDisplay_Click(object sender, EventArgs e)
    {
        SqlConnection myConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString);
        myConnection.Open();
        try
        {
            SqlDataReader reader = null;
            string serverIP = drpChoose.SelectedItem.Value.ToString();
            SqlCommand cmd = new SqlCommand("SELECT * from ScheduledTasks WHERE ServerIP = " + serverIP, myConnection);
            reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                GridView1.DataSource = reader;
                GridView1.DataBind();
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.ToString());
        }
        myConnection.Close();
    }
    public void Populate()
    {
        SqlConnection myConnection1 = new SqlConnection(ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString);
        myConnection1.Open();
        SqlCommand cmd1 = new SqlCommand("SELECT ServerIP FROM Servers", myConnection1);
        SqlDataReader dropReader;
        dropReader = cmd1.ExecuteReader();
        drpChoose.DataSource = dropReader;
        drpChoose.DataTextField = "ServerIP";
        drpChoose.DataValueField = "ServerIP";
        drpChoose.DataBind();
    }
}

只是一个指南：为什么不使用Ajaxtoolkit UpdatePanel控件。将Gridview放在UpdatePanel中，然后将下拉选择设置为Gridview的Updatetrigger。这样您就不必担心回发和值了。

将Page_Load方法更改为：

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack()) {
        Populate();
    }
}

每次加载页面时，都会重新绑定下拉选择，以便始终设置默认的"all"值。通过使用Page.IsPostBack属性，您告诉页面只在第一次加载时绑定，而不在随后的回发时绑定。通过使用此属性，在回发时下拉列表中选定的项目将不会更改。

MSDN：Page.IsPostBack

更新

关于您对SQL语句中"Where"子句的评论，serverIP是否以文本形式存储在数据库中？尝试用撇号包装serverIP，如：

SqlCommand cmd = new SqlCommand("SELECT * from ScheduledTasks WHERE ServerIP = '" + serverIP + "'', myConnection);
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