How to retrieve every combination of numbers from 2 columns - mysql

Question

I'm trying to find a way to retrieve every combination of values from two columns in a table, where each combination matches a value in a third column.
Say part of the table looks like this:
products_id options_id options_values_id
1487 2 1
1487 2 61
1487 3 60
1487 5 52
My desired output, when working with products_id 1487, would be the following two strings:
2-1, 3-60, 5-52
2-61, 3-60, 5-52
I've got the impression that those strings would need to be assembled recursively, but I ran into trouble trying it that way because not every products_id has the same options_ids, or the same number of them.
Edited to add: I've tried variations of a couple of the solutions below, but to no avail. I think I should have been more descriptive.
I'm trying to have it retrieve every combination of unique options_id and its corresponding options_values_id. (In other words, not every single possible combination of numbers from those two columns.) Options_id represents product options like "color" and "size," and options_values_id represents choices of those options, like "red" or "small." So I'm trying to come up with every possible combination of options for a given products_id. In the example above, there are two possible option combinations for that item-- "2-1, 3-60, 5-52" and "2-61, 3-60, 5-52".

Answer 1

Join the table against itself for each distinct option.
Do a select first to retrieve the number of options.
$tables = array();
$rs = mysql_query(
'SELECT DISTINCT options_id FROM table WHERE products_id = '.$id);
while ($row = mysql_fetch_row($rs)) {
$tables[$row['options_id']] =
'SELECT options_values_id FROM table WHERE products_id = '.$id.
' AND options_id = '.$row['options_id'];
}
mysql_free_result($rs);
Then, for each option, join it in as a separate table in your query. Do not include any joining clauses comparing values, just join every record against every other record.
$sql = 'SELECT ';
$count = 0;
foreach ($tables AS $id => $query) {
if ($count++) $sql .= ', ;
$sql .= 'table_'.$id.'.options_values_id AS value_'.$id;
}
$sql .= ' FROM ';
$count = 0;
foreach ($tables AS $id => $query) {
if ($count++) $sql .= ', ';
$sql .= '('.$query.') AS table_'.$id;
}
Finally, execute that query. Each row will contain one column per options_id. There will be one row per unique combination of values.

Answer 2

or for a mixed, php/sql approach, try using that SQL query:
SELECT products_id, options_id, options_values_id WHERE products_id = '$var_with_product_id';
fetch the results into an array, say $results:
$pairs = array();
foreach($results as $result) {
// build array with pairs (array_push to avoid overwriting)
array_push($pairs, array( $result['options_id'] => $result['options_values_id'];
}
// a bit extra complication, as array_push adds e.g. [0] => array( options_id => options_values_id ) :)
$pairs = array_values($pairs);
// check for double options_id
$found_double_options_id = false;
do {
// check for duplicates... use a lot of array functions
} while (count($pairs) && $found_double_options_id);

Answer 3

"Every combination" is the Cartesian product:
SELECT DISTINCT e1.options_id, e2.options_values_id
FROM Entity e1, Entity e2
WHERE e1.products_id = 1487 AND e2.products_id=1487