As a feature request can c3p0 instead of requiring the user to enter the
preferredTestQuery, supply a preferredTestQuery for each driver? If the user
wants to override the preferredTestQuery the option is still there, though
it would be nice to have a default.
# for MySQL/PostgreSQL/MS SQL use: SELECT 1
# for Oracle use: SELECT 1 from dual
# for DB2 use: SELECT 1 FROM sysibm.sysdummy1