count generation, maybe loop until?

[Tanja]

In my database are following fields: id, fatherid, motherid.

There are four "starter-dogs" with id 1,2,3 and 4; now i want to count how many generations are between the starter and the dog (for each starter seperate).

 

How can i loop the query (and count) until it reach id 1 (or 2)?

 

Select fatherid from mytable where id = 222

Result (for example) 333 - not 1 - again

Select fatherid from mytable where id = 333 ...

[requinix]

Sure: keep getting the fatherid in a loop until you end up with one of the starter dog IDs.

$id = 222
while $id is not of a starter dog {
	$id = get fatherid of $id
}

(or another similar loop construct)

[Tanja]

ok, but here are same dogs more than one time in pedigree (the starter dogs).

On father side the starterdog is in the 6. generation, on mother side in 9. generation.

With this solution a called every fatherid so long until starter dog is reached (for father, grandfather, grandgrand...)

 

I want the shortest distance to the starter dog...

http://www.wolfdog-database.com/dog/dog.php?id=13425&gens=7

 

for example here the shortest distance to Sarik. In other cases the pedigree is over much more generations ;-)

[requinix]

Breadth-first search: every time you find a non-starter dog, append it to an array (as well as the "depth"). Use a while/array_shift() loop to keep pulling stuff off the array (you can't foreach) until you find a starter dog.

$dogs = array(current dog);
while($dog = array_shift($dogs)) {
	list($dog, $depth) = $dog;
	if $dog is a starter dog {
		return $depth;
	} else {
		$dogs[] = array($dog''s mother, $depth + 1);
		$dogs[] = array($dog''s father, $depth + 1);
	}
}