DBI consults several environment variables, listed in Table H.4. All of them except DBI_TRACE are used by the connect() method. DBI_DRIVER is used by the data_sources() method, and DBI_TRACE is used by trace().
Name
Meaning
DBI_DRIVER
DBD-level driver name ("mysql" for MySQL)
DBI_DSN
Data source name
DBI_PASS
Password
DBI_TRACE
Trace level and/or trace output file
DBI_USER
Username
