my %prepares = (
    table1 => $dbh->prepare("insert table1 (...) values (?, ...)",
    table2 => $dbh->prepare("insert table2 (...) values (?, ...)",
   # and so on
);
# Now process the file
open FILE, '<', $wherever;
while (<FILE>)
{
    # set $table and @values from $_
    $prepares{$table}->execute(@values);
}