8.8. Using Microsoft Entity Frameworks to Access MySQL Schema Objects with Virtuoso
Abstract
This section details the steps required to provide Microsoft Entity Framework access to MySQL Schema Objects using the OpenLink Virtuoso Universal Server. This is achieved by linking the required MySQL 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 MySQL Schema objects linked into the Virtuoso Server.
Prerequisites. The following prerequisites must be in place for this solution to be possible.
MySQL DBMS. An MySQL DBMS hosting the required Schema Objects needs to be available. In this section the Northwind sample database will be used to demonstrate the process.
An MySQL DBMS hosting the required Schema Objects needs to be available. In this section the Northwind sample database will be used to demonstrate the process.
ODBC Driver for MySQL. An MySQL ODBC Driver is required for Linking the MySQL Schema Objects into the Virtuoso Server. The OpenLink ODBC Driver for MySQL will be used in this section, for which a functional ODBC Data source name of "mysqlma" will be assumed to exist on the machine hosting the Virtuoso Server.
An MySQL ODBC Driver is required for Linking the MySQL Schema Objects into the Virtuoso Server. The OpenLink ODBC Driver for MySQL will be used in this section, for which a functional ODBC Data source name of "mysqlma" 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
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.
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.
Tasks
Ensure MySQL Primary Keys (PKs) are not nullable. The Visual Studio 2008 Entity Data Model (EDM) requires that all primary keys are NOT Nullable, and will fail to generate an EDM if any are. Thus ensure any tables to be used are defined as not nullable in the MySQL database schema before attempting to generate an EDM. In the case of the Northwind database all tables are not nullable, thus this should not be an issue in this case.
The Visual Studio 2008 Entity Data Model (EDM) requires that all primary keys are NOT Nullable, and will fail to generate an EDM if any are. Thus ensure any tables to be used are defined as not nullable in the MySQL database schema before attempting to generate an EDM. In the case of the Northwind database all tables are not nullable, thus this should not be an issue in this case.
8.8.1. Install and configure OpenLink ODBC Driver for MySQL
The Virtuoso Virtual Database engine uses ODBC as the connectivity mechanism for linking remote database objects into its local schema. Thus an MySQL ODBC Driver must be available with a suitably configured DSN for connecting to the target database. The OpenLink ODBC Drivers for MySQL have been used in this section, although in theory any MySQL ODBC Driver can be used.
Installation instructions for the OpenLink ODBC Driver for MySQL are available from: