ask about checkboxlist

Question

i want to store checked items of check box list in database and i got the code but it did not work when i run this code it does not show items in database column rather than it shows "checkbox.DataValueField" in database..code snippet is given below...

kindly help me ... 

public partial class courses : System.Web.UI.Page

{

    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);

    protected void Page_Load(object sender, EventArgs e)

    { }

    protected void SqlDataSource1_Selecting(object sender, SqlDataSourceSelectingEventArgs e)

    { string interests = string.Empty;

        foreach (ListItem item in this.checkbox.Items)

            if (item.Selected)

            {

                interests += item.Text;

                SqlCommand cmd = new SqlCommand("Insert into tbl3(courseId) values('" + interests + "')", con); //Write Your Query to insert into database table

                con.Open();

                int iCount = cmd.ExecuteNonQuery();

                con.Close();

            }

    }

}