I have a MySQL database with data in it that I'll call rules. It's basically a map for a perl program that finds a rule based on the results of the previous rule. For example, rule 1 is run and based on the output (return) and the stages, the table is used to determine the next rule to run and stages to "be in." Here is a very simple example of the table: 
* return * rule * stage1 * stage2 * next_rule * next_stage1 * next_stage2 *
***************************************************************************
*   ret1 *    1 *     A  *     00 *         2 *           B *          10 *
*   ret2 *    1 *     A  *     00 *         5 *           D *          23 *
*   bob1 *    2 *     B  *     10 *         5 *           D *          23 *
*   bob2 *    2 *     B  *     10 *         6 *           E *          44 *
*   dog1 *    3 *     B  *     10 *         6 *           E *          44 *
*   dog2 *    4 *     C  *     10 *         6 *           E *          44 *
*   cat1 *    5 *     D  *     23 *         7 *           F *          55 *
*   cat2 *    5 *     D  *     23 *         7 *           F *          56 *
*   cat3 *    5 *     D  *     23 *         7 *           F *          57 *
*   hit1 *    6 *     E  *     44 *         7 *           G *          55 *
*   hit1 *    6 *     K  *     14 *         7 *           H *          55 *
*   hit2 *    6 *     E  *     44 *         7 *           G *          56 *
*   etc.
***************************************************************************
What I'd like to do is create a representation of the tree and the different possible paths. I was thinking I could use a hash and each set of possible returns would be another level in the hash. Let's say I start off running rule 1 in stage1 A and stage2 00. This is the hash I'm trying to get to: 
$hash{ret1}             = { rule => '1', stage1 => 'A', stage2 => '00', next_rule => '2', next_stage1 => 'B', next_stage2 => '10' };
$hash{ret1}{bob1}       = { rule => '2', stage1 => 'B', stage2 => '10', next_rule => '5', next_stage1 => 'D', next_stage2 => '23' };
$hash{ret1}{bob1}{cat1} = { rule => '5', stage1 => 'D', stage2 => '23', next_rule => '7', next_stage1 => 'F', next_stage2 => '55' };
$hash{ret1}{bob1}{cat2} = { rule => '5', stage1 => 'D', stage2 => '23', next_rule => '7', next_stage1 => 'F', next_stage2 => '56' };
$hash{ret1}{bob1}{cat3} = { rule => '5', stage1 => 'D', stage2 => '23', next_rule => '7', next_stage1 => 'F', next_stage2 => '57' };
$hash{ret1}{bob2}       = { rule => '2', stage1 => 'B', stage2 => '10', next_rule => '6', next_stage1 => 'E', next_stage2 => '44' };
$hash{ret1}{bob2}{hit1} = { rule => '6', stage1 => 'E', stage2 => '44', next_rule => '7', next_stage1 => 'G', next_stage2 => '55' };
$hash{ret1}{bob2}{hit2} = { rule => '6', stage1 => 'E', stage2 => '44', next_rule => '7', next_stage1 => 'G', next_stage2 => '56' };
$hash{ret2}             = { rule => '1', stage1 => 'A', stage2 => '00', next_rule => '5', next_stage1 => 'D', next_stage2 => '23' };
$hash{ret2}{cat1}       = { rule => '5', stage1 => 'D', stage2 => '23', next_rule => '7', next_stage1 => 'F', next_stage2 => '55' };
$hash{ret2}{cat2}       = { rule => '5', stage1 => 'D', stage2 => '23', next_rule => '7', next_stage1 => 'F', next_stage2 => '56' };
$hash{ret2}{cat3}       = { rule => '5', stage1 => 'D', stage2 => '23', next_rule => '7', next_stage1 => 'F', next_stage2 => '57' };
These trees will get up to 20 elements deep. I was thinking I could just keep going through the last set of keys, grab the rows from the table and append the next set of keys. The problem is I can't figure out how to use that last set. If I've traversed down to $hash{ret1}{bob1}, I'll select from my table all rows where rule => '5', stage1 => 'D', and stage2 => '23' and get cat1, cat2, and cat3. How do I say "ok, now create $hash{ret1}{bob1}{cat1}, $hash{ret1}{bob1}{cat2}, and $hash{ret1}{bob1}{cat3}?

Hopefully what I'm trying to do makes sense. If you have a better way to create a structure of this data that I can then use to print or diagram with, that's great too. This is just the way I thought the result would make for an easily traversed "tree" when done.

In reply to Getting hash key tree by jhisey

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