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DBI.pm  view on Meta::CPAN

the DBI to effectively do a C<die("$class $method failed: $DBI::errstr")>,
where C<$class> is the driver class and C<$method> is the name of the method
that failed. E.g.,

  DBD::Oracle::db prepare failed: ... error text here ...

If you turn C<RaiseError> on then you'd normally turn C<PrintError> off.
If C<PrintError> is also on, then the C<PrintError> is done first (naturally).

Typically C<RaiseError> is used in conjunction with C<eval { ... }>
to catch the exception that's been thrown and followed by an
C<if ($@) { ... }> block to handle the caught exception.
For example:

  eval {
    ...
    $sth->execute();
    ...
  };
  if ($@) {
    # $sth->err and $DBI::err will be true if error was from DBI

DBI.pm  view on Meta::CPAN

above. The error code and error string will be recorded in the
handle and available via C<$h-E<gt>err> and C<$DBI::errstr> etc.
The set_err() method always returns an undef or empty list as
approriate. Since your method should nearly always return an undef
or empty list as soon as an error is detected it's handy to simply
return what set_err() returns, as shown in the example above.

If the handle has C<RaiseError>, C<PrintError>, or C<HandleError>
etc. set then the set_err() method will honour them. This means
that if C<RaiseError> is set then set_err() won't return in the
normal way but will 'throw an exception' that can be caught with
an C<eval> block.

You can stash private data into DBI handles
via C<$h-E<gt>{private_..._*}>.  See the entry under L</ATTRIBUTES
COMMON TO ALL HANDLES> for info and important caveats.


=head1 TRACING

The DBI has a powerful tracing mechanism built in. It enables you