Introduction to ODBC
Corporations typically have applications and data residing on diverse platforms and database management systems due to historical, strategic or technological reasons. The Microsoft Open database connectivity (ODBC) is a de facto standard interface for accessing data in a heterogeneous environment of relational and non-relational database management systems.
ODBC is based on a specification, which was developed by a consortium of over 40 companies (members of the SQL Access Group and others), and has broad support from application and database vendors.

ODBC provides an open, vendor-neutral way of accessing data stored in a variety of proprietary personal computers, minicomputers and mainframe databases. With ODBC, an application can concurrently access, view, and modify data from multiple, diverse databases. ODBC provides many significant benefits to developers and end users by providing an open, standard way to access data:

• ODBC allows corporations to continue to use their existing database management systems, while enabling access to their data by common applications.
• ODBC benefits users as more end-user applications connect to additional data sources, making the vast volumes of corporate data more readily available.
• ODBC allows users to access data in more than one data storage location (for example, more than one server) from within a single application.
• ODBC allows users to access data in more than one type of DBMS (such as DB2, Oracle, Eloquence, and dBASE) from within a single application.
• ODBC provides a standard, open, and vendor-neutral API.
• ODBC allows corporations and software vendors to protect their investments in existing DBMSs.
• ODBC is based upon the SQL Access Group (SAG) Call Level Interface (CLI) and provides a standard SQL language based upon ANSI standards.

How ODBC Works
ODBC defines a data base independend standard how applications can interact with a data base. A Driver Manager sits between the application and the data base specific drivers. In Windows, the Driver Manager and the drivers are implemented as dynamic-link libraries (DLLs).

The application (eg. MS Office or MS Access) calls ODBC functions to connect to a data source, send and receive data, and disconnect.

The Driver Manager provides information to an application such as a list of available data sources; loads drivers dynamically as they are needed; and provides argument and state transition checking.

The driver, developed separately from the application, sits between the application and the network. The driver processes ODBC function calls, manages all exchanges between an application and a specific DBMS, and may translate the standard SQL syntax into the native SQL of the target data source. All SQL translations are the responsibility of the driver developer.

Applications are not limited to communicating through one driver. A single application can make multiple connections, each through a different driver, or multiple connections to similar sources through a single driver.

To access a new DBMS, a user or an administrator installs a driver for the DBMS. The user does not need a different version of the application to access the new DBMS. This is a tremendous benefit for end users, as well as providing significant savings for IT organizations in support and development costs.

Summary
ODBC defines a standard SQL grammar and set of function calls that are based upon the SAG CLI specification, called the core grammar and core functions, respectively. If an application developer chooses only to use the core functionality, they need not write any additional code to check for specific capabilities of a driver.
With core functionality, an application can:

• Establish a connection with a data source, execute SQL statements,
  and retrieve results.
• Receive standard error messages.
• Provide a standard login interface to the end user.
• Use a standard set of data types defined by ODBC.
• Use a standard SQL grammar defined by ODBC.

ODBC also defines an extended SQL grammar and set of extended functions to provide application developers with a standard way to exploit advanced capabilities of a DBMS. Finally, ODBC supports the use of DBMS-specific SQL grammar, allowing applications to exploit the capabilities of a particular DBMS.

Prerequisites
The following are prerequisites to the installation of the SQL/R ODBC driver.

Prerequisites for the Server system
• HP 9000 (PA-RISC or Itanium2), Linux or Windows NT/2000/XP
• HP-UX Release 10.20 or later
• ELOQUENCE Version A.03.10 or later
• Approx. 10 MB available memory in the /opt file system

Prerequisites for the client system
• Windows 95/98/NT/2000/XP
• TCP/IP network protocol stack compliant with the WINSOCK 1.1 standard
.
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