The drivers must be defined in your CLASSPATH variable. The CLASSPATH is the search string your Java Virtual Machine (JVM) uses to locate JDBC drivers on your computer. If the drivers are not defined on your CLASSPATH, you will receive a class not found exception when trying to load the driver. Set your system CLASSPATH to include the driver jar file as shown, where driver.jar is the driver jar file (for example, sqlserver.jar) and install_dir is the path to your product installation directory: