Introduction
Today, in this article let's play around with an interesting and very useful concept in Entity Framework.
Question: What is Table per Type Inheritance?
In simple terms "The parent entity is associated with many child entities where the child entities can inherit the data from the parent. Here the primary key of the parent entity is shared with the child entity that maintains a 1-1 relationship".
Step 1: Create a new web application
![Output1.jpg]()
Step 2: Entities in the DB looks like this:
![Output2.png]()
Step 3: Adding New Entity Data Model Framework
![Output3.jpg]()
Step 4: Select the tables from the DB
![Output4.png]()
Step 5: Entity in Model Browser
![Output5.png]()
Step 6: Delete association links between entities
![Output6.png]()
Step 7: Select the base types
![Output7.png]()
![Output8.png]()
Step 8: New inheritance associations established
![Output9.png]()
Step 10: Delete the child table or entities Ids that will inherit from the parent entity
![Output10.png]()
Step 11: The complete code of WebForm1.aspx looks like this:
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="TPTInheritanceInsertEFApp.WebForm1" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<center>
<table>
<tr>
<td>
<asp:Label ID="Label1" runat="server" Text="Insert Data with TPT Inheritance via EDM Framework"
Font-Bold="true"></asp:Label>
</td>
</tr>
</table>
<br />
<br />
<table>
<tr>
<td>
<asp:Label ID="Label2" runat="server" Text="Please Enter Transport Info: " ForeColor="Brown"
Font-Bold="true" Font-Italic="true"></asp:Label>
</td>
<td>
<asp:TextBox ID="TextBox1" runat="server" Width="117px"></asp:TextBox>
</td>
</tr>
<tr>
<td>
<asp:Label ID="Label3" runat="server" Text="Please Select Transport Mode: " ForeColor="Brown"
Font-Bold="true" Font-Italic="true"></asp:Label>
</td>
<td>
<asp:DropDownList ID="DropDownList1" runat="server" Width="117px">
<asp:ListItem Text="Train" Value="0"></asp:ListItem>
<asp:ListItem Text="Bus" Value="1"></asp:ListItem>
</asp:DropDownList>
</td>
</tr>
<tr>
<td>
<asp:Label ID="Label4" runat="server" Text="Please Enter Transport Code: " ForeColor="Brown"
Font-Bold="true" Font-Italic="true"></asp:Label>
</td>
<td>
<asp:TextBox ID="TextBox2" runat="server" Width="117px"></asp:TextBox>
</td>
</tr>
<tr>
<td colspan="2" align="center">
<asp:Button ID="Button1" runat="server" Text="Insert Data" OnClick="Button1_Click"
BackColor="Orange" Font-Bold="true" /><br />
<br />
</td>
</tr>
</table>
<br />
<br />
<table>
<tr>
<td colspan="3">
<asp:Label ID="Label5" runat="server" Font-Bold="true"></asp:Label>
</td>
</tr>
</table>
</center>
</div>
</form>
</body>
</html>
Step 12: The complete code of WebForm1.aspx.cs looks like this:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;namespace TPTInheritanceInsertEFApp
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))
{
Label5.Text = "Please Enter Some Values";
Label5.ForeColor = System.Drawing.Color.Red;
}
else
{
switch (int.Parse(DropDownList1.SelectedValue))
{
case 0:Train objTrain = new Train()
{
TransportMode = DropDownList1.SelectedItem.Text, TransportCode = TextBox2.Text, TrainInfo = TextBox1.Text };
objEntities.AddToTransport(objTrain);
objEntities.SaveChanges();
Label5.Text = "Train Details Inserted Sucessfully";
Label5.ForeColor = System.Drawing.Color.Green;
TextBox1.Text = string.Empty;
TextBox2.Text = string.Empty;
break;case 1:Bus objBus = new Bus()
{
TransportMode = DropDownList1.SelectedItem.Text, TransportCode = TextBox2.Text, BusInfo = TextBox1.Text
};
objEntities.Transport.AddObject(objBus);
objEntities.SaveChanges();
Label5.Text = "Bus Details Inserted Sucessfully";
Label5.ForeColor = System.Drawing.Color.Green;
TextBox1.Text = string.Empty;
TextBox2.Text = string.Empty;
break;
}
}
}
#region Instance MembersCompanyEntities objEntities = new CompanyEntities();
#endregion
}
}
Step 13: The output of the application looks like this:
![Output11.png]()
Step 14: The inserted data output of the application looks like this:
![Output12.png]()
Step 15: The data inserted in parent entity output of the application looks like this:
![Output13.png]()
Step 16: The data inserted in child entity output of the application looks like this:
![Output14.png]()
I hope this article was useful for you.