A en C verbonden?

SELECT a.id FROM a INNER JOIN b INNER JOIN c ON (b.aid = a.id AND c.bid = b.id) WHERE a.id=1

SELECT a.id FROM a INNER JOIN b INNER JOIN c ON (b.aid = a.id AND c.bid = b.id) WHERE a.id=1

SELECT COUNT(a.id) 
FROM a 
INNER JOIN b
INNER JOIN c
ON (a.punt = b.punt OR b.punt = c.punt OR a.punt = c.punt) 
WHERE a.punt=$punt OR b.punt=$punt OR c.punt=$punt

SELECT COUNT(a.id) 
FROM a 
INNER JOIN b
INNER JOIN c
ON (a.punt = b.punt OR b.punt = c.punt OR a.punt = c.punt) 
WHERE a.punt=$punt OR b.punt=$punt OR c.punt=$punt

SELECT 
  COUNT(tableA.id) as records,
  tableA.name as mainName
FROM
  tableNameA as tableA,
  tableNameB as tableB,
  tableNameC as tableC
WHERE
  tableA.id = $iInputID AND
  tableA.id = tableB.id AND
  tableB.id = tableC.id
GROUP BY
  tableA.id

SELECT 
  COUNT(tableA.id) AS records,
  tableA.name AS mainName
FROM
  tableNameA AS tableA,
  tableNameB AS tableB,
  tableNameC AS tableC
WHERE
  tableA.id = $iInputID AND
  tableA.id = tableB.id AND
  tableB.id = tableC.id
GROUP BY
  tableA.id

function isConnected($begin, $end) {
	$result = mysql_query('SELECT `beginpunt_id`, `eindpunt_id` FROM `verbindingen`');
	$data = array();
	while ($row = mysql_fetch_row($result)) {
		$min = min($row);
		$max = max($row);
		$data[$min][] = $max;
	}
	if (isset($data[$begin])) {
		$stack[] = $data[$begin];
		while (count($stack) > 0) {
			$bondings = array_shift($stack);
			foreach (array_unique($bondings) as $bonding) {
				if ($bonding == $end) {
					return true;
				} elseif (isset($data[$bonding])) {
					$stack[] = $data[$bonding];
				}
			}
		}
	}
	return false;
}

function isConnected($begin, $end) {
	$result = mysql_query('SELECT `beginpunt_id`, `eindpunt_id` FROM `verbindingen`');
	$data = array();
	while ($row = mysql_fetch_row($result)) {
		$min = min($row);
		$max = max($row);
		$data[$min][] = $max;
	}
	if (isset($data[$begin])) {
		$stack[] = $data[$begin];
		while (count($stack) > 0) {
			$bondings = array_shift($stack);
			foreach (array_unique($bondings) as $bonding) {
				if ($bonding == $end) {
					return true;
				} elseif (isset($data[$bonding])) {
					$stack[] = $data[$bonding];
				}
			}
		}
	}
	return false;
}

CREATE TABLE `punten` (
  `id` smallint(6) NOT NULL auto_increment,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1238 DEFAULT CHARSET=utf8;

CREATE TABLE `verbindingen` (
  `id` smallint(6) NOT NULL auto_increment,
  `beginpunt_id` smallint(6) default NULL,
  `eindpunt_id` smallint(6) default NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3004 DEFAULT CHARSET=utf8;

CREATE TABLE `punten` (
  `id` smallint(6) NOT NULL AUTO_INCREMENT,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1238 DEFAULT CHARSET=utf8;
 
CREATE TABLE `verbindingen` (
  `id` smallint(6) NOT NULL AUTO_INCREMENT,
  `beginpunt_id` smallint(6) DEFAULT NULL,
  `eindpunt_id` smallint(6) DEFAULT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3004 DEFAULT CHARSET=utf8;