当你选定一项进行其他操作时会重新绑定dropdownlist，这样会重新回到第一项，在page_load里加上判断if(!IsPostBack){‘这里是你需要绑定dropdownlist的代码‘}。

private void Page_Load(object sender, System.EventArgs e)

{

if (!IsPostBack)

{

bindtodropdownlist1();//第一种方法

bindtodropdownlist2();//第二种方法

}

}

//第一种方法

private void bindtodropdownlist1()

{

string connstring=”data source=SINOSOFT-SERVER;initial catalog=kmsdb;user id=mbm;password=mbm”;

string querystring=”select distinct cDepartmentname from t_Department”;

SqlConnection myconn=new SqlConnection(connstring);

myconn.Open();

SqlDataAdapter myadapter=new SqlDataAdapter(querystring,myconn);

DataSet ds=new DataSet();

myadapter.Fill(ds,”t_Department”);

myconn.Close();

DropDownList1.DataSource=ds.Tables[0].DefaultView;

DropDownList1.DataValueField=ds.Tables[“t_Department”].Columns”cDepartmentName”].ToString();

DropDownList1.DataBind();

}

//第二种方法

private void bindtodropdownlist2()

{

string connstring=”data source=SINOSOFT-SERVER;initial catalog=kmsdb;user id=kms;password=kms”;

string querystring=”select distinct cDepartmentname from t_Department”;

SqlConnection myconn=new SqlConnection(connstring);

myconn.Open();

SqlCommand myCommand = new SqlCommand(querystring,myconn);

SqlDataReader myReader;

myReader = myCommand.ExecuteReader();// Always call Read before accessing data.

while (myReader.Read())

{

DropDownList2.Items.Add(new ListItem(myReader.GetString(0),myReader.GetString(0)));

}

myReader.Close();

myconn.Close();

}

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