c# - 如何从asp.net的下拉列表中的数据库绑定(bind)选定的值

我正在尝试从下拉列表的数据库中绑定选定的项目。我没有在下拉列表中让用户选择数据，而是加载了所有内容。我需要的是从数据库中获得默认的选定值以及其他项目。请帮助我克服这个问题。预先感谢您。

存储过程：

CREATE PROCEDURE [dbo].[get_student_details]
  @StudentId int = 0
AS
BEGIN
    SET NOCOUNT ON;

    SELECT
        dbo.Student.InstituteId,
        dbo.Student.Institute,
        dbo.Student.Name,
        dbo.Student.Gender,
        dbo.Student.Age
    FROM
        dbo.Student
    WHERE
        dbo.Student.StudentId = @StudentId
END

我的.aspx标记：

<asp:DropDownList ID="ddlInstitute" runat="server"></asp:DropDownList>
<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
<asp:TextBox ID="txtGender" runat="server"></asp:TextBox>
<asp:TextBox ID="txtAge" runat="server"></asp:TextBox>
<asp:Button ID="btnPersonalDetails" runat="server"  Text="Search" OnClick="GetStudentDetails"/>

我后面的代码：

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        FillInstitute();
    }
}

public void FillInstitute()
{
    SqlConnection con = new SqlConnection(constr);
    SqlCommand cmd = new SqlCommand();
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.CommandText = "get_Institute";
    cmd.Connection = con;

    try
    {
        con.Open();
        ddlInstitute.DataSource = cmd.ExecuteReader();
        ddlInstitute.DataTextField = "Institute";
        ddlInstitute.DataValueField = "InstituteId";
        ddlInstitute.DataBind();
        ddlInstitute.Items.Insert(0, new ListItem("--Select--", "0"));
    }
    catch (Exception ex)
    {
        throw ex;
    }
    finally
    {
        con.Close();
        con.Dispose();
    }
}

public void GetStudentDetails()
{
    studentid= 123;
    SqlConnection con = new SqlConnection(constr);
    SqlCommand cmd = new SqlCommand();
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.CommandText = "get_student_details";
    cmd.Parameters.Add("@StudentId", SqlDbType.Int).Value = studentid;
    cmd.Connection = con;

    try
    {
        con.Open();
        SqlDataReader dr = cmd.ExecuteReader();

        if (dr.Read())
        {
            ddlInstitute.DataValueField= dr["InstituteId"].ToString();
            ddlInstitute.DataTextField= dr["Institute"].ToString();
            txtName.Text = dr["Name"].ToString();
            txtGender.Text = dr["Gender"].ToString();
            txtAge.Text = dr["Age"].ToString();
        }
    }
    catch (Exception ex)
    {
        throw ex;
    }
    finally
    {
        con.Close();
        con.Dispose();
    }
}

最佳答案

您必须使用SelectedValue的DropDownList属性。DataTextField和DataValueField用于指定DataSource中的哪些属性应用作文本和下拉列表的值。

替换这些行：

ddlInstitute.DataValueField= dr["InstituteId"].ToString();
ddlInstitute.DataTextField= dr["Institute"].ToString();

与：

ddlInstitute.SelectedValue= dr["InstituteId"].ToString();

或者您也可以：

ddlInstitute.Items.FindByValue(dr["InstituteId"].ToString()).Selected = true;

您也可以参考this article

关于c# - 如何从asp.net的下拉列表中的数据库绑定(bind)选定的值，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/32528561/