如何使用DBD :: mysql和Perl检查数据库行是否存在？

use DBI;
use DBD::mysql;

my $dbh = DBI->connect("DBI:mysql:database=<database_name>;host=<hostname>;port=<port>", "<username>", "<password>")
  or die "无法连接到数据库: $DBI::errstr";

my $query = "SELECT * FROM <table_name> WHERE <condition>";

my $sth = $dbh->prepare($query);
$sth->execute();

if ($sth->rows > 0) {
    print "行存在\n";
} else {
    print "行不存在\n";
}

$sth->finish();
$dbh->disconnect();