将值从组合框中插入到SQL Server

Question

In my DB I have two tables ( Employee and Team ). The Team table has two columns ( ID , TeamName ) and it's displayed in an asp.net page as a dropdown.

<asp:DropDownList ID="team_id" runat="server" CssClass="form-control"></asp:DropDownList>

From my asp.net page I need to insert a row into the employee table which includes teamID .

Below is set team combo box code

private void SetTeamComboBox()
    {
        DataTable tableVariable = GetTeam();
        team_id.DataTextField = "TEAMNAME";
        team_id.DataValueField = "ID";
        team_id.DataSource = tableVariable;

        //MANUALLY ADD ROW
        DataRow dr = tableVariable.NewRow();
        dr["TEAMNAME"] = "Select TEAM";
        dr["ID"] = 0;
        tableVariable.Rows.InsertAt(dr, 0);
        team_id.SelectedIndex = 0;
        team_id.DataBind();
    }

public DataTable GetTeam()
    {
        SqlConnection oleconnectionVariable = new SqlConnection(conString);
        SqlCommand commandVariable = new SqlCommand();
        commandVariable.CommandText = "SELECT ID,TEAMNAME FROM TEAM";
        commandVariable.Connection = oleconnectionVariable;
        oleconnectionVariable.Open();
        SqlDataAdapter adapterVariable = new SqlDataAdapter(commandVariable);
        DataSet dataSet = new DataSet();
        adapterVariable.Fill(dataSet);

        adapterVariable.Dispose();
        commandVariable.Dispose();
        oleconnectionVariable.Dispose();
        return dataSet.Tables[0];//WE NEED TO GET THE DATATABLE  
    }

I need to insert the ID of the team but I'm getting an error on the following line.

commandVariable.Parameters.AddWithValue("@TeamID",Convert.ToInt32(team_id.SelectedValue));

team id is always ZERO (see debugging image below)

Answer 1

I think you are calling SetTeamComboBox() in Page_Load() event so every time DropDownBox control status changed. The problem in postback which not handled.

Solution:

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