如何在asp.net和C#中填充dropdownlist [英] how to fill dropdownlist in asp.net and c#

问题描述

你好，
我编写了以下代码来填充下拉列表"ddlstuid".
下面的代码给我一个错误:"ddlstuid的最佳重载方法匹配有一些无效的参数".请告诉我如何使用c#代码在asp.net中填充下拉列表.

Hello,
I have written the following code to fill the dropdownlist ''ddlstuid''.
The following code gives me an error: "The best overloaded method match for ddlstuid has some invalid arguments". Pls tell me how else can i fill a dropdownlist in asp.net using c# code.

SqlConnection myconn;
SqlCommand cmd;
string str = "Data Source=TIMSCDR\\SQLEXPRESS;Initial Catalog=IAP;Integrated Security=True";
SqlDataReader dr;

     try
    {
        cmd = new SqlCommand("select stuid from attendance", myconn);
        myconn.Open();
        ddlstuid.Items.Clear();
        dr = cmd.ExecuteReader();
        if (dr != null)
        {
            while (dr.Read())
            {
                ddlstuid.Items.Add(dr["stuid"]);
            }
        }
        myconn.Close();
    }
    catch (Exception e1)
    {
        Label45.Text = "Error ocurred" + e1;
    }

推荐答案

ddlstuid.Items.Add(dr["stuid"].tostring());
 Convert this into the String

有多种方法可以做到这一点:
1)您可以使用DataAdapter和DataTable:

There are a number of ways to do this:
1) You could use a DataAdapter and DataTable:

SqlDataAdapter da = new SqlDataAdapter("SELECT stuid FROM attendance", myconn);
DataTable dt = new DataTable();
da.Fill(dt);
ddlstuid.Items.Clear();
ddlstuid.DataSource = dt;

2)您可以构造一个列表并使用它:

2) You could construct a list and use that:

try
    {
    cmd = new SqlCommand("select stuid from attendance", myconn);
    myconn.Open();
    ddlstuid.Items.Clear();
    dr = cmd.ExecuteReader();
    List<object> list = new List<object>();
    if (dr != null)
        {
        while (dr.Read())
            {
            list.Add(dr["stuid"]);
            }
        }
    myconn.Close();
    ddlstuid.DataSource = list;
    }
catch (Exception e1)
    {
    Label45.Text = "Error ocurred" + e1;
    }

就个人而言，我更喜欢前者...

Personally, I prefer the former...

您需要将dr ["stuid"])转换为字符串，如下所示:


dr ["stuid"]).toString()

you need to convert dr["stuid"]) into string as:


dr["stuid"]).toString()

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