Ensure that the jConnect driver is in your class file path. The driver file jconn4.jar is located in the classes subdirectory of your jConnect installation.
set classpath=.;c:\jConnect-7_0\classes\jconn4.jar;%classpath%
The jConnect driver takes advantage of the new automatic JDBC driver registration. The driver is automatically loaded at execution startup when it is in the class file path.