How to Access Sybase Data Using Entity Framework

Microsoft Entity Framework serves as an object-relational mapping framework for working with data represented as objects. Although Visual Studio offers the ADO.NET Entity Data Model wizard to automatically generate the Entity Model, this model-first approach may present challenges when your data source undergoes changes or when you require greater control over entity operations. In this article, we will delve into the code-first approach for accessing Sybase data through the CData ADO.NET Provider, providing you with more flexibility and control.

1. Open Visual Studio and create a new Windows Form Application. This article uses a C# project with .NET 4.5.
2. Run the command 'Install-Package EntityFramework' in the Package Manger Console in Visual Studio to install the latest release of Entity Framework.

3. Modify the App.config file in the project to add a reference to the Sybase Entity Framework 6 assembly and the connection string.

   To connect to Sybase, specify the following connection properties:

   • Server: Set this to the name or network address of the Sybase database instance.
   • Database: Set this to the name of the Sybase database running on the specified Server.

   Optionally, you can also secure your connections with TLS/SSL by setting UseSSL to true.

   Sybase supports several methods for authentication including Password and Kerberos.

   Connect Using Password Authentication

   Set the AuthScheme to Password and set the following connection properties to use Sybase authentication.

   • User: Set this to the username of the authenticating Sybase user.
   • Password: Set this to the username of the authenticating Sybase user.

   Connect using LDAP Authentication

   To connect with LDAP authentication, configure Sybase server-side to use the LDAP authentication mechanism.

   After configuring Sybase for LDAP, you can connect using the same credentials as Password authentication.

   Connect Using Kerberos Authentication

   To leverage Kerberos authentication, begin by enabling it setting AuthScheme to Kerberos. See the Using Kerberos section in the Help documentation for more information on using Kerberos authentication.

   You can find an example connection string below:

   Server=MyServer;Port=MyPort;User=SampleUser;Password=SamplePassword;Database=MyDB;Kerberos=true;KerberosKDC=MyKDC;KerberosRealm=MYREALM.COM;KerberosSPN=server-name

   <configuration>
    ... 
    <connectionStrings>
    <add name="SybaseContext" connectionString="Offline=False;User=myuser;Password=mypassword;Server=localhost;Database=mydatabase;Charset=iso_1;" providerName="System.Data.CData.Sybase" />
    </connectionStrings>
    <entityFramework>
    <providers>
    ... 
    <provider invariantName="System.Data.CData.Sybase" type="System.Data.CData.Sybase.SybaseProviderServices, System.Data.CData.Sybase.Entities.EF6" />
    </providers>
    <entityFramework>
   </configuration>
   </code> 
   

4. Add a reference to System.Data.CData.Sybase.Entities.EF6.dll, located in the lib -> 4.0 subfolder in the installation directory.
5. Build the project at this point to ensure everything is working correctly. Once that's done, you can start coding using Entity Framework.
6. Add a new .cs file to the project and add a class to it. This will be your database context, and it will extend the DbContext class. In the example, this class is named SybaseContext. The following code example overrides the OnModelCreating method to make the following changes:
   • Remove PluralizingTableNameConvention from the ModelBuilder Conventions.
   • Remove requests to the MigrationHistory table.

   using System.Data.Entity;
   using System.Data.Entity.Infrastructure;
   using System.Data.Entity.ModelConfiguration.Conventions;
   
   class SybaseContext : DbContext {
    public SybaseContext() { }
   
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
    // To remove the requests to the Migration History table
    Database.SetInitializer<SybaseContext>(null); 
    // To remove the plural names 
    modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
    } 
   }
   

7. Create another .cs file and name it after the Sybase entity you are retrieving, for example, Products. In this file, define both the Entity and the Entity Configuration, which will resemble the example below:

   using System.Data.Entity.ModelConfiguration;
   using System.ComponentModel.DataAnnotations.Schema;
   
   [System.ComponentModel.DataAnnotations.Schema.Table("Products")]
   public class Products {
    [System.ComponentModel.DataAnnotations.Key] 
    public System.String Id { get; set; }
    public System.String ProductName { get; set; }
   }
    
   

8. Now that you have created an entity, add the entity to your context class:

   public DbSet<Products> Products { set; get; }
   

9. With the context and entity finished, you are now ready to query the data in a separate class. For example:

   SybaseContext context = new SybaseContext();
   context.Configuration.UseDatabaseNullSemantics = true;
   var query = from line in context.Products select line;