ODBC [Open Database Connectivity]
ODBC is a standard database access method developed by Microsoft Corporation. ODBC makes it possible to access data from any application, regardless of which database management system (DBMS) is handling the data. ODBC is based on the Call-Level Interface [CLI] specifications from X/Open and ISO/IEC for database APIs and uses Structured Query Language [SQL] as its database access language. The functionality of ODBC involves the insertion of a middle layer, called a database driver, between an application and the DBMS. The purpose of the database driver is to translate the application’s data queries into commands that the DBMS understands. To access an ODBC database, you must have the appropriate ODBC driver for the database you wish to access. To access data provided by a data source, a connection to the data source must first be established. All data access is managed through that connection.
The ODBC architecture has four components:
- Application. Performs processing and calls ODBC functions to submit SQL statements and retrieve results.
- Driver Manager. Loads and unloads drivers on behalf of an application. Processes ODBC function calls or passes them to a driver.
- Driver. Processes ODBC function calls, submits SQL requests to a specific data source, and returns results to the application. If necessary, the driver modifies an application’s request so that the request conforms to syntax supported by the associated DBMS.
- Data source. Consists of the data the user wants to access and its associated operating system, DBMS, and network platform (if any) used to access the DBMS.
The following illustration shows the relationship between these four components.