try this

package MyDB;
use base 'Class::DBI';
__PACKAGE__->set_db(...);
# other table junk setup
__PACKAGE__->set_sql('getlastid', 'SELECT @@identity',...);   # see pe
+rldoc Ima::DBI
...
1;

# then where you need the last id you can try

my ($id) = MyDBI->sql_getlastid()->execute();

# or something close (again see Ima::DBI)
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