Using Microsoft Entity Frameworks to Access Ingres Schema Objects with Virtuoso

This document details the steps required to provide Microsoft Entity Framework access to Ingres Schema Objects using the OpenLink Virtuoso Universal Server. This is achieved by linking the required Ingres Schema objects into Virtuoso using its built-in Virtual Database engine and then using the Virtuoso ADO.NET Entity Framework provider to query the remote Ingres Schema objects linked into the Virtuoso Server.


The following prerequisites must be in place for this solution to be possible.

Ingres DBMS

An Ingres DBMS hosting the required Schema Objects needs to be available. In this document, the Ingres Tutorial sample database will be used to demonstrate the process.

ODBC Driver for Ingres

An Ingres ODBC Driver is required for Linking the Ingres Schema Objects into the Virtuoso Server. The OpenLink ODBC Driver for Ingres will be used in this document, for which a functional ODBC Data source name of ingiima will be assumed to exist on the machine hosting the Virtuoso Server.

Virtuoso Universal Server

An Virtuoso installation including the Virtuoso Universal Server and ADO.NET Entity Framework Provider is required. The Virtuoso components used must be Release 5.10.x or above, this being the minimum version containing support for Microsoft Entity Frameworks.

Microsoft Visual Studio 2008 SP1

Microsoft Visual Studio 2008 Service Pack 1 is required, this being the only version containing the necessary Entity Framework support available at the time of writing.


Ensure Ingres Primary Keys (PKs) are not nullable

The Visual Studio 2008 Entity Data Model (EDM) requires that all primary keys are NOT Nullable. Visual Studio 2008 will fail to generate an EDM, if any are. Therefore, ensure any tables to be used are defined as not nullable in the Ingres database schema before attempting to generate an EDM. In the case of the Ingres Tutorial database, all primary keys are not nullable. Thus, this should not be an issue in this case.

Install and configure OpenLink ODBC Driver for Ingres

The Virtuoso Virtual Database engine uses ODBC as the connectivity mechanism for linking remote database objects into its local schema. Thus, an Ingres ODBC Driver must be available with a suitably configured DSN for connecting to the target database. The OpenLink ODBC Drivers for Ingres have been used in this document, although in theory any Ingres ODBC Driver can be used.

Installation instructions for the OpenLink ODBC Driver for Ingres are available from:

Install and configure OpenLink Virtuoso Universal Server

Linking Ingres tables into Virtuoso

Creating Visual Studio hosted Entity Data Model (EDM)

In the event that no entity-linking associations are automatically created (as is the case here with Ingres), the associations will need to be created manually. The following document details this process —

Using EDM to create Entity Framework based applications

Now that a Microsoft Entity Data Model has been created for the Ingres Tutorial database, Entity Framework applications can be created to make use of it.

Entity Frameworks based ADO.NET Data Service
Visual Studio Windows Form Application

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