log4perl.appender.app_db.datasource = sub { \
   require DBI; \
   my $connect_info = "dbi:SQLite:uri=file:log4perl.sqlite"; \
   my $dbh = DBI->connect($connect_info); \
   # ERROR handling, possible DB	creation left out! \
   $dbh->do(<<"_SQL_"); \
       CREATE TABLE IF NOT EXISTS log (	\
      	   # ... table definition	.... \
       ); \
_SQL_ \
   $connect_info; \
}