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LINQ to Presto Data

LINQ provides general-purpose query facilities in .NET Framework 3.0 and above and provides one easy way to programmatically access data through from CData ADO.NET Data Providers. This example uses LINQ to access information from the Presto Data Provider.

This article demonstrates how to use LINQ to access Presto tables through the CData ADO.NET Data Provider for Presto. To do this you will LINQ to Entity Framework, which is used to generate the connection and can be used with any CData ADO.NET Data Providers to access data via LINQ.

See the help documentation for a guide to setting up an EF 6 project to use the provider.

  1. In a new project in Visual Studio, right-click on the project and choose to add a new item. Add an ADO.NET Entity Data Model.
  2. Choose EF Designer from Database and click Next.
  3. Add a new Data Connection, and change your data source type to "CData Presto Data Source".
  4. Enter your data source connection information.

    Set the Server and Port connection properties to connect, in addition to any authentication properties that may be required.

    To enable TLS/SSL, set UseSSL to true.

    Authenticating with LDAP

    In order to authenticate with LDAP, set the following connection properties:

    • AuthScheme: Set this to LDAP.
    • User: The username being authenticated with in LDAP.
    • Password: The password associated with the User you are authenticating against LDAP with.

    Authenticating with Kerberos

    In order to authenticate with KERBEROS, set the following connection properties:

    • AuthScheme: Set this to KERBEROS.
    • KerberosKDC: The Kerberos Key Distribution Center (KDC) service used to authenticate the user.
    • KerberosRealm: The Kerberos Realm used to authenticate the user with.
    • KerberosSPN: The Service Principal Name for the Kerberos Domain Controller.
    • KerberosKeytabFile: The Keytab file containing your pairs of Kerberos principals and encrypted keys.
    • User: The user who is authenticating to Kerberos.
    • Password: The password used to authenticate to Kerberos.

    Below is a typical connection string:

    Server=127.0.0.1;Port=8080;
  5. If saving your entity connection to App.Config, set an entity name. In this example we are setting PrestoEntities as our entity connection in App.Config.
  6. Enter a model name and select any tables or views you would like to include in the model.

Using the entity you created, you can now perform select , update, delete, and insert commands. For example:

PrestoEntities context = new PrestoEntities(); var customerQuery = from customer in context.Customer select customer; foreach (var result in customerQuery) { Console.WriteLine("{0} {1} ", result.Id, result.FirstName); }

See "LINQ and Entity Framework" chapter in the help documentation for example queries of the supported LINQ.