如何将下拉控件绑定到 ASP.NET 中的数据源

Question

我是 C# 新手。

我有一个创建 HR 系统的项目，我创建了一个页面来添加员工，但主管要求我创建一个下拉列表，在添加新员工时显示部门。

我不知道如何开始以及首先应该做什么。我已经从工具中添加了一个下拉列表，但我不知道如何选择数据源以及它的名称和值。我应该选择部门表还是员工表？

public partial class _Default : Page
{

    private String strcon = ConfigurationManager.ConnectionStrings["hr"].ConnectionString;

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

            bindgrideview();
    }
    protected void bindgrideview()
    {
        SqlConnection strcon1 = new SqlConnection(strcon);
        strcon1.Open();
        string ADDStr = "SELECT F_name , L_name , salary FROM Employee ";
        SqlCommand ADDCmd = new SqlCommand(ADDStr, strcon1);
        DataTable table = new DataTable();


        SqlDataAdapter adapter = new SqlDataAdapter(ADDCmd);

        adapter.Fill(table);
        GridView1.DataSource = table;
        GridView1.DataBind();

    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        string F_name = TextBox1.Text;
        string L_name = TextBox2.Text;
        int status = 1;
        string salarystr = TextBox3.Text.ToString();
        int salary = Int32.Parse(salarystr);
        SqlConnection strcon1 = new SqlConnection(strcon);
        strcon1.Open();
        string ADDStr = "ADDEMP";
        SqlCommand ADDCmd = new SqlCommand(ADDStr, strcon1);
        ADDCmd.CommandType = CommandType.StoredProcedure;
        ADDCmd.Parameters.AddWithValue("@F_name", F_name);
        ADDCmd.Parameters.AddWithValue("@L_name", L_name);
        ADDCmd.Parameters.AddWithValue("@status", status);
        ADDCmd.Parameters.AddWithValue("@salary", salary);

        ADDCmd.ExecuteNonQuery();
        bindgrideview();
        TextBox1.Text = "";
        TextBox2.Text = "";
    }

这是我页面的屏幕截图： http://store2.up-00.com/Nov12/YXb11858.png

这是最后的代码，没有错误，但下拉列表没有项目:(

public partial class _Default : Page
{

    private String strcon = ConfigurationManager.ConnectionStrings["hr"].ConnectionString;

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

            bindgrideview();
    }
    protected void bindgrideview()
    {
        SqlConnection strcon1 = new SqlConnection(strcon);
        strcon1.Open();
        string ADDStr = "SELECT F_name , L_name , salary FROM Employee ";
        SqlCommand ADDCmd = new SqlCommand(ADDStr, strcon1);
        DataTable table = new DataTable();


        SqlDataAdapter adapter = new SqlDataAdapter(ADDCmd);

        adapter.Fill(table);
        GridView1.DataSource = table;
        GridView1.DataBind();

    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        string F_name = TextBox1.Text;
        string L_name = TextBox2.Text;
        int status = 1;
        string salarystr = TextBox3.Text.ToString();
        int salary = Int32.Parse(salarystr);
        SqlConnection strcon1 = new SqlConnection(strcon);
        strcon1.Open();
        string ADDStr = "ADDEMP";
        SqlCommand ADDCmd = new SqlCommand(ADDStr, strcon1);
        ADDCmd.CommandType = CommandType.StoredProcedure;
        ADDCmd.Parameters.AddWithValue("@F_name", F_name);
        ADDCmd.Parameters.AddWithValue("@L_name", L_name);
        ADDCmd.Parameters.AddWithValue("@status", status);
        ADDCmd.Parameters.AddWithValue("@salary", salary);

        ADDCmd.ExecuteNonQuery();
        bindgrideview();
        TextBox1.Text = "";
        TextBox2.Text = "";
        TextBox3.Text = "";
    }
    protected void bindDepartments()
    {
        SqlConnection strcon1 = new SqlConnection(strcon);
        strcon1.Open();
        string ADDStr = "SELECT ID,department_name FROM Department ";
        SqlCommand ADDCmd = new SqlCommand(ADDStr, strcon1);
        DataTable table = new DataTable();


        SqlDataAdapter adapter = new SqlDataAdapter(ADDCmd);

        adapter.Fill(table);

        DropDownList1.DataSource = table;
        DropDownList1.DataValueField = "ID";
        DropDownList1.DataTextField = "department_name";
        DropDownList1.DataBind();

    }

}

Answer 1

由于您的代码可用于检索 Employees 信息。从数据库中，您将检索到 Departments 信息。从您的部门表中。

protected void bindDepartments()
{
    SqlConnection strcon1 = new SqlConnection(strcon);
    strcon1.Open();
    string ADDStr = "SELECT DepartmentId,DepartmentName FROM Departments ";
    SqlCommand ADDCmd = new SqlCommand(ADDStr, strcon1);
    DataTable table = new DataTable();


    SqlDataAdapter adapter = new SqlDataAdapter(ADDCmd);

    adapter.Fill(table);

    ddlDepartments.DataSource = table;
    ddlDepartments.DataValueField = "DepartmentId"; //The Value of the DropDownList, to get it you should call ddlDepartments.SelectedValue;
    ddlDepartments.DataTextField = "DepartmentName"; //The Name shown of the DropDownList.
    ddlDepartments.DataBind();

}