trace()
$handle->trace(level[,log]) |DBI->trace()
This method sets the trace level for a handle. A level of 0
disables tracing; level 1 traces the execution of the database handle;
level 2 provides more details including parameter values. If a
filename is given as the second argument, trace information will be
appended to that log file instead of stderr. If
DBI->trace() syntax is used instead of a
statement handle, it will set the trace level globally. It will return
the trace settings it had before it was called as well.