DropdownList绑定的两种方法

动态绑定方法一：动态绑定数据库中的字段。

SqlConnection conn = UtilitySqlClass.OperateDataBase.ReturnConn();
string strSQL = "select * from CompanyType";
SqlDataAdapter ada = new SqlDataAdapter(strSQL, conn);
DataSet ds = new DataSet();
ada.Fill(ds, "CompanyType");
DropDownList1.DataSource = ds.Tables["CompanyType"].DefaultView;
DropDownList1.DataValueField = ds.Tables["CompanyType"].Columns[1].ColumnName;
DropDownList1.DataTextField = ds.Tables["CompanyType"].Columns[1].ColumnName;
DropDownList1.DataBind();
ds.Dispose();

动态绑定方法二：利用DropDownList.Items.Add方法。

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
SqlConnection conn = UtilitySqlClass.OperateDataBase.ReturnConn();
try
{
conn.Open();
this.DropDownList1.Items.Add("");
string strSQL = "select CompanyType from CompanyType";
SqlCommand com = new SqlCommand(strSQL, conn);
SqlDataReader dr = com.ExecuteReader();
while (dr.Read())
{
this.DropDownList1.Items.Add(dr["CompanyType"].ToString());
}
}
catch (Exception ex)
{
Response.Write("<scirpt>alert('" + ex.Message.ToString() + "')</script>");
}
finally
{
conn.Close();
}
}
}

第一种方法：
        string ConnString = ConfigurationSettings.AppSettings["ConnectionString"];
         //创建一个SqlConnection
         SqlConnection Conn = new SqlConnection( ConnString );

string SQL_Select = "select id, ItemName from DDLItem order by id desc";

//构造一个SqlDataAdapter

SqlDataAdapter myAdapter = new SqlDataAdapter( SQL_Select, Conn);

//開始读取数据

Conn.Open();

DataSet dataSet = new DataSet();

myAdapter.Fill( dataSet,"Table1" );

Conn.Close();

//開始绑定DropDownList

//指定DropDownList使用的数据源

DropDownList1.DataSource = dataSet.Tables["Table1"].DefaultView;

//指定DropDownList使用的表里的那些字段

DropDownList1.DataTextField = "ItemName"; //dropdownlist的Text的字段

DropDownList1.DataValueField = "id";//dropdownlist的Value的字段

DropDownList1.DataBind();

另外一种方法：
        con.Open();
        SqlCommand cmd = new SqlCommand(strSql,con);
        SqlDataReader dr = cmd.ExecuteReader();
        while (dr.Read())
        {     
            DropDownList1.Items.Add(new ListItem(dr["status"].ToString(), dr["status_Id"].ToString()));
        }