DropDownList 中的值不会保存到 SQL Server 表中

Question

I have a DropDownList that gets populated by a SQL Server table called tblVisa . My issue is that the values that are being populated from the SQL Server table are not being saved. Everything else gets saved except for my DropDownLists. I've tried using .SelectedValue and .Text , but it still does not work.

Here is my code

protected void PopulateVisaType()
{
        List<ListItem> result = new List<ListItem> { new ListItem("", "") };

        SqlCommand cmd = new SqlCommand() { Connection = sqlConn, CommandText = "SELECT VisaType FROM tblVisa ORDER BY VisaType ASC" };

        if (sqlConn.State == ConnectionState.Closed) 
        {
            sqlConn.Open(); 
        }

        SqlDataReader read = cmd.ExecuteReader();

        while (read.Read())
        {
            result.Add(new ListItem(read["VisaType"].ToString(), read["VisaType"].ToString()));
        }

        read.Close();
        sqlConn.Close();
        cmd.Dispose();

        DDLVisa.DataSource = result;
        DDLVisa.DataValueField = "value";
        DDLVisa.DataTextField = "text";
        DDLVisa.DataBind();
}

Here's my code for saving the information into the database:

protected void LbSaveProfile_Click(object sender, EventArgs e)
{
    SqlCommand cmd = new SqlCommand() { Connection = sqlConn, CommandText = "spSaveNewProviderInformation", CommandType = CommandType.StoredProcedure };

    if (sqlConn.State == ConnectionState.Closed)
    { 
        sqlConn.Open(); 
    }

    cmd.Parameters.AddWithValue("@EmployeeNumber", TbEmployeeNumber.Text.Trim());
    cmd.Parameters.AddWithValue("@SSN", TbSSN.Text.Trim());
    cmd.Parameters.AddWithValue("@ContractType", DDLContractType.SelectedItem.Value);
    cmd.Parameters.AddWithValue("@Firstname", TbFirstname.Text.Trim());
    cmd.Parameters.AddWithValue("@Lastname", TbLastname.Text.Trim());
    cmd.Parameters.AddWithValue("@MiddleInitial", TbMiddleInitial.Text.Trim());
    cmd.Parameters.AddWithValue("@ContractRenewalDate", TbContractRenewalDate.Text.Trim());
    cmd.Parameters.AddWithValue("@Position", DDLPosition.Text.Trim());
    cmd.Parameters.AddWithValue("@Specialty", DDLSpecialty.Text.Trim());
    cmd.Parameters.AddWithValue("@PrimaryDepartment", DDLPrimaryDepartment.Text.Trim());
    cmd.Parameters.AddWithValue("@SecondaryDepartment", DDLSecondaryDepartment.Text.Trim());
    cmd.Parameters.AddWithValue("@Gender", DDLGender.Text.Trim());
    cmd.Parameters.AddWithValue("@Birthdate", TbBirthdate.Text.Trim());
    cmd.Parameters.AddWithValue("@EmailAddress", TbEmailAddress.Text.Trim());
    cmd.Parameters.AddWithValue("@PhoneNumber", TbPhoneNumber.Text.Trim());
    cmd.Parameters.AddWithValue("@Address", TbAddress.Text.Trim());
    cmd.Parameters.AddWithValue("@PassportNumber", TbPassportNumber.Text.Trim());
    cmd.Parameters.AddWithValue("@Citizenship", DDLCitizenship.Text.Trim());
    cmd.Parameters.AddWithValue("@Visa", DDLVisa.Text.Trim());
    cmd.Parameters.AddWithValue("@Status", 1);

    cmd.ExecuteNonQuery();

    sqlConn.Close();

    Alert("Provider Information saved!");

    ClearControls();
}

Answer 1

You much better to provide the drop down list with column names.

So, say this:

    protected void PopulateVisaType()
    {
        SqlConnection sqlConn = new SqlConnection("");

        using (SqlCommand cmd = new SqlCommand("SELECT VisaType FROM tblVisa ORDER BY VisaType ASC", sqlConn))
        {
            if (sqlConn.State == ConnectionState.Closed)
            {
                sqlConn.Open();
            }

            DDLVisa.DataSource = cmd.ExecuteReader();
            DDLVisa.DataValueField = "VisaType";
            DDLVisa.DataTextField = "VisaType";

            DDLVisa.DataBind();
            //DDLVisa.Items.Insert(0, new ListItem(""));   // optional blank row choice

            sqlConn.Close();
        }
    }

So the TextField, and the DataText field need to be a named column from the data source.

I also included an optional first blank option if you need/want/expect to have no choice.

However, keep in mind that this empty string should be translated into a null in your database if you don't allow (or want) empty strings, and want a null for that value. This applies to all of your values. (perhaps the stored procedure does this?).