c# - C#：如何在更改另一个下拉列表时更改下拉列表的内容？

Question

我是 C# 新手，我正在尝试了解如何在更改另一个下拉列表时更改一个下拉列表的内容？如下所示，我当前的尝试不成功，因此我们将不胜感激任何建议或帮助。

protected void drpDwnSchool_TextChanged(object sender, EventArgs e)
{
    drpDwnTeacher.Items.Clear();
    string selectedSchool = drpDwnSchool.SelectedValue.ToString();
    String sqlQueryTeacher = "SELECT * FROM Teacher WHERE SchoolName = '" + selectedSchool + "'";
    SqlConnection sqlConnect = new SqlConnection(WebConfigurationManager.ConnectionStrings["Lab1"].ToString());
    SqlCommand sqlCommand1 = new SqlCommand();
    sqlCommand1.Connection = sqlConnect;
    sqlCommand1.CommandType = CommandType.Text;
    sqlCommand1.CommandText = sqlQueryTeacher;
    sqlConnect.Open();
    SqlDataReader queryResultsTeacher = sqlCommand1.ExecuteReader();
    while (queryResultsTeacher.Read())
    {
        string LastName = queryResultsTeacher["LastName"].ToString();
        drpDwnTeacher.Items.Add(queryResultsTeacher["LastName"].ToString());
    }
   sqlConnect.Close();
}

标签： c#sqlasp.net

Answer 1

它没有填充第二个列表吗？如果是这样，请尝试“SelectedIndexChanged”事件而不是更改文本。