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Entity Framework Code First: Mapping to Existing Table in the Database

, 30 Sep 2013
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This tip is about how to connect with existing table in the database.

Introduction

This tip is about how to connect with an existing table in the database.

Background

For learning Code First, you can refer to the following:

Using the Code

The database name is MyClass and it consists of only one table "ClassAll".

Below is ClassAll class with the same attributes and properties as of the table .

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace School.Data.Model
{
    public partial class ClassAll
    {
          
        public int SchoolRollNo { get; set; }
        public int Standard { get; set; }
        public int ClassRollNo { get; set; }
        public string Name { get; set; }
        public string Gender { get; set; }
        public int Percentage { get; set; }
        public System.DateTime Date { get; set; }
    }
}

The class ClassAllMap is used to map with the existing table in the database.

using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.ModelConfiguration;

namespace School.Data.Model.Mapping
{
    public class ClassAllMap : EntityTypeConfiguration<ClassAll>
    {
        public ClassAllMap()
        {
            // Primary Key
            this.HasKey(t => t.SchoolRollNo);

            // Properties
            this.Property(t => t.SchoolRollNo)
                .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

            this.Property(t => t.Name)
                .IsRequired()
                .HasMaxLength(50);

            this.Property(t => t.Gender)
                .IsRequired()
                .IsFixedLength()
                .HasMaxLength(10);

            // Table & Column Mappings
            this.ToTable("ClassAll");
            this.Property(t => t.SchoolRollNo).HasColumnName("SchoolRollNo");
            this.Property(t => t.Standard).HasColumnName("Standard");
            this.Property(t => t.ClassRollNo).HasColumnName("ClassRollNo");
            this.Property(t => t.Name).HasColumnName("Name");
            this.Property(t => t.Gender).HasColumnName("Gender");
            this.Property(t => t.Percentage).HasColumnName("Percentage");
            this.Property(t => t.Date).HasColumnName("Date");
        }
    }
}

MyClassContext is the reference to the "MySchool" database. In this code, we are using the ClassAllMap declared above for configuration.

using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using School.Data.Model.Mapping;

namespace School.Data.Model
{
    public partial class MyClassContext : DbContext
    {
        static MyClassContext()
        {
            Database.SetInitializer<MyClassContext>(null);
        }

        public MyClassContext()
            : base("Name=MyClassContext")
        {
        }

        public DbSet<ClassAll> ClassAlls { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new ClassAllMap()); 
        }
    }
}

If using SQL Server Express Edition, in web.config file, add the connection string as follows:

<connectionStrings> 
    <add name="MyClassContext" providerName="System.Data.SqlClient" 
       connectionString="Server=.\SQLEXPRESS;Database=MyClass;Trusted_Connection=true;" />
</connectionStrings>

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Shubham Chakraborty
Software Developer (Junior)
India India
No Biography provided

Comments and Discussions

 
Questionhow about EF code first migration PinmemberMahdi Ghafoorian27-Apr-14 4:58 
GeneralMy vote of 1 Pinmemberzeewon23-Mar-14 1:56 
GeneralMy vote of 1 PinmemberMember 28141395-Feb-14 1:11 

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