Using the InterSystems ODBC Driver
InterSystems provides ODBC drivers to enable you to access InterSystems databases via an ODBC connection. To use ODBC, install and configure the InterSystems ODBC client driver, then define one or more DSNs to refer to InterSystems databases. Your application can use an InterSystems DSN in the same way it would use any other DSN.
To use an InterSystems database as an ODBC data source, you should first ensure that the InterSystems ODBC client driver has been installed. The following options are available:
On Windows, InterSystems IRIS IDs use the Large Number (BigInt
) datatype, so ODBC client applications must have Large Number support. For example, instances of Access 2016 previous to build 16.0.7812 will display row data as #Deleted
. This may also happen if Large Number support is not turned on in the Access Settings for the current database.
The InterSystems ODBC drivers are compliant with ODBC 3.5.
InterSystems ODBC supports the following ODBC driver managers:
On Windows: the Microsoft Windows driver manager provided with the operating system.
On UNIX®: the iODBC driver manager (for use with the Unicode and 8bit ODBC APIs) and the unixODBC driver manager (for use with the 8bit ODBC API).
An ODBC system has the following components:
The client application
An application makes calls according to the Microsoft ODBC API. ODBC calls establish a connection from the client to a data source (see the section on “ODBC Connection Details
The ODBC driver manager
The driver manager accepts calls from applications using the ODBC API and hands them off to a registered ODBC client driver. The driver manager also performs any necessary tasks so that the client application can communicate with the client driver and, ultimately, the database server.
The ODBC client driver
A database-specific application that accepts calls from a client application through the ODBC driver manager and provides communication to the database server. It also performs any ODBC-related data conversions that the application requests.
The database server
The actual database ultimately receiving the calls from the client application. It can be on the same or a different machine than the client driver from which it is receiving calls.
An initialization file
A set of configuration information for the driver manager; depending on the operating system, it may also contain client driver information. On UNIX®, this is an actual file, frequently called odbc.ini
. On Windows, it is a registry entry.
For a particular vendor database, that vendor may offer its own version of the ODBC client driver for that platform. Oracle, for example, supplies its own ODBC driver for use with Oracle databases on Windows. This may be preferred in some cases because the vendor driver may take advantage of its knowledge of how the database works internally to optimize performance or enhance reliability.
For an application to connect to a database via ODBC, the application must generally provide the following connection details:
Information about the ODBC client driver to use.
Information on locating and accessing the database. For example, this may include the server on which the database resides and the port to use when connecting to it. The details needed depend upon the database technology.
Login credentials to access the database, if the database is protected by a password.
In most cases, this information is stored within a DSN, which has a logical name for use within the client application. The DSN may or may not include login credentials, which can also be stored in the database initialization file, or not stored at all.
The DSNs must be registered with the ODBC driver manager.
In practice, a connection is established as follows:
A client application includes ODBC calls that attempt to connect to a particular DSN. A client application is linked to an ODBC driver manager, which accepts the calls.
The ODBC driver manager reads the initialization file to obtain the location of the ODBC client driver and load the client driver into memory.
Once loaded into memory, the ODBC client driver uses the ODBC initialization file to locate connection information for the DSN, as well as other information. Using this information, the client driver connects to the specified database.
Having established the connection, the client driver maintains communications with the database server.
Content Date/Time: 2019-02-18 00:56:44