Question

Hey guys, I have an issue whereby only my parent is being inserted into DB, am i missing something? heres my code snippet

public partial class linqtest : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            MyContext db = new MyContext("Server=(local);Database=Test;User ID=admin;Password=pw");
            Child c = new Child();
            c.name = "joe "+DateTime.Now;
            db.parents.InsertOnSubmit(c);
            db.SubmitChanges();
        }
    }

    public class MyContext : DataContext
    {
        public static DataContext db;
        public MyContext(string connection) : base(connection) { }
        public Table<Parent> parents;
    }

    [Table(Name="parents")]
    [InheritanceMapping(Code = "retarded", Type = typeof(Child), IsDefault=true)]
    public class Parent
    {
        [Column(Name = "id", IsPrimaryKey = true, CanBeNull = false, DbType = "Int NOT NULL IDENTITY", IsDbGenerated = true)] /* I want this to be inherited by subclasses */
        public int id { get; set; }

        [Column(Name = "name", IsDiscriminator = true)] /* I want this to be inherited by subclasses */
        public string name { get; set; }
    }

    public class Child : Parent
    {

    }

Answer 1

What you are describing where you have have one table for a Parent object and another table for a Child object is called “multiple table inheritance” or “table per subtype”…and, unfortunately, it is not supported by Linq-to-SQL. See the SO question Multiple Inheritance in LINQtoSQL? and my own question looking for work-arounds at Simulating Multiple Table Inheritance in Linq-to-SQL. You can also Google “table inheritance in linq-to-sql” to see how to do single table inheritance in Linq-to-SQL, which is supported.