Types of ODBC drivers

When PowerBuilder is connected to an ODBC data source, you might see messages from the ODBC driver that include the words single-tier or multiple-tier. These terms refer to the two types of drivers defined by the ODBC standard.

Single-tier driver

A single-tier ODBC driver processes both ODBC functions and SQL statements. In other words, a single-tier driver includes the data access software required to manage the data source file and catalog tables. An example of a single-tier ODBC driver is the Microsoft Access driver.

Figure 2-2: Single-tier ODBC driver

The figure illustrates a single tier ODBC driver within the context of the components of an ODBC connection. The diagram shows boxes interconnected with arrows. They include an application, ODBC Driver Manager, single-tier ODBC driver, and Data source. Within the rectangle labeled single-tier ODBC driver is a rectangle labeled data access software.

Multiple-tier driver

A multiple-tier ODBC driver processes ODBC functions, but sends SQL statements to the database engine for processing. Unlike the single-tier driver, a multiple-tier driver does not include the data access software required to manage the data directly.

An example of a multiple-tier ODBC driver is the Sybase SQL Anywhere driver.

Figure 2-3: Multi-tier ODBC driver

The figure illustrates a multi tier ODBC driver within the context of the components of an ODBC connection. The diagram shows boxes interconnected with arrows. They include an application, ODBC Driver Manager, multiple tier ODBC driver, a database engine, and a Data source. Within the rectangle labeled database engine is a rectangle containing Data access software.