在php mysql中获取有关其父母关系的孩子的所有详细信息

Question

Cat and sub category Table (cat_tbl) :

id | cat_n    | parent_id
1  |   cat    |  0
2  |   dog    |  0
3  |   tiger  |  2
4  |   lion   |  0
5  |   abc    |  0
6  |   bcd    |  3 

Now i have a product table as below (prod_tbl) :

id  | pwght | cid  |  cpid 
10  |  1.2  |  1   |   0
11  |  2.4  |  2   |   0
12  |  3.4  |  2   |   0
13  |  4.5  |  6   |   3

and user final weight product table is below (userprod_tbl) :

id | pwght | cid  |  cpid | prod_id ( is above prod_tbl primary id )
1  |  1.1  |  1   |   0   |  10
2  |  2.3  |  2   |   0   |  11
3  |  3.1  |  3   |   2   |  12
4  |  4.0  |  6   |   3   |  13

RESULT : ( OUTPUT WHICH I WANT ) IS comparison of prod_tbl with userprod_tbl as below :

 Prod tbl                  Userprod tbl

 cat  1.2                  cat                 1.1

 dog  2.4                  dog   --     --     2.3
 dog  3.4                  dog  tiger   --     3.1
 dog  4.5                  dog  tiger  bcd     4.0      

Hence in above result 2.4,3.4,4.5 are belong to Parent id 2

But i am getting as below

 Prod tbl                  Userprod tbl

 cat  1.2                  cat                 1.1

 dog  2.4                  dog   --     --     2.3
 dog  3.4                  dog  tiger   --     3.1   

in above result i am not getting 4.5 value ,as 4.5 has 6,3 relation from above prod table but its parent of id 2

Below is my query which i have return:

SELECT pt.pwght , upt.pwght ,ct.cat_n,uct.cat_n,umct.cat_n
FROM prod_tbl AS pt
LEFT JOIN userprod_tbl AS upt ON (pt.id = upt.prod_id)
LEFT JOIN cat_tbl AS ct ON pt.packet_id = ct.id
LEFT JOIN cat_tbl AS uct ON upt.packet_id = uct.id
LEFT JOIN cat_tbl AS umct ON upt.parent_packet_id = umct.id

Please let me know what is missing Thanks

Answer 1

This will solve your problem I think.

SELECT pt.pwght AS prod_pwght, upt.pwght AS userprod_pwght ,
       ct.cat_n AS prod_catName,uct.cat_n AS Userprod_catName
FROM prod_tbl AS pt
LEFT JOIN userprod_tbl AS upt ON pt.id = upt.prod_id
LEFT JOIN cat_tbl AS ct ON pt.cid = ct.id
LEFT JOIN cat_tbl AS uct ON upt.cid = uct.id;

here is working fiddle for you - http://sqlfiddle.com/#!9/9568a/1

Answer 2

You cannot translate recursion into SQL. You could make your query increasingly complex to cover this recursion up to a determined number of levels, but not to an undetermined number, and doing that is very slow and completely unecessary.

I suggest you fetch cat_tbl to your script and compute this category ladder localy instead of imposing that on MySQL.

Example (Please note I'm just writing this without testing anything):

$cat_tree = [];

$res = $mysql->query('SELECT id, cat_n, parent_id FROM cat_tbl');
while ($row = $res->fetch_row())
    $cat_tree[$row[0]] = [$row[1], $row[2]];

function get_tree($cid)
{
    global $cat_tree;

    $result = [$cat_tree[$cid][1]];
    while ($cat_tree[$cid][2])
    {
        $cid = $cat_tree[$cid][2];
        $result[] = $cat_tree[$cid][1];
    }
    return array_reverse($result);
}

$res = $mysql->query('SELECT pt.id, pt.cid, pt.pwght, ut.cid, ut.pwght FROM prod_tbl pt INNER JOIN userprod_tbl ut ON pt.id = u.prod_id');
while ($row = $res->fetch_row())
{
    $ptree = get_tree($row[1]);
    $utree = get_tree($row[3]);
    printf("%s | %f | %s | %s\n", $ptree[0], $row[2], implode(', ', $utree), $row[4]);
}

This should output something like:

cat | 1.2 | cat | 1.1
dog | 2.4 | dog | 2.3
dog | 3.4 | dog, tiger | 3.1
dog | 4.5 | dog, tiger, bcd | 4.0