t1 products:
id, name, pri, usw
1, beispiel1, x.xx
2, beispiel1, x.xx
3, beispiel1, x.xx
4, beispiel1, x.xx

t2 pr_calc:
id, pid, name
1, 2, test1, x.xx
2, 2, test2, x.xx
3, 2, test3, x.xx
4, 4, dieses, x.xx
5, 4, jenes, x.xx
6, 4, sonstiges, x.xx
7, 4, alles, x.xx 

SELECT 
   products.id, 
   products.name, 
   products.pri,  
   COUNT(pr_calc.pid) AS prc_anz, 
   pr_calc.id AS prc_id, 
   pr_calc.name AS prc_name, 
   pr_calc.pri AS prc_pri 
FROM 
   products 
LEFT OUTER JOIN 
   pr_calc ON pr_calc.pid = products.id 
GROUP BY 
   products.id, 
   pr_calc.id 
ORDER BY 
  products.id ASC

Array
(
    [id] => 1
    [name] => Beispiel1
    [pri] => 149.00
    [prc_anz] => 0
    [prc_id] => 
    [prc_name] => 
    [prc_pri] =>
)

Array
(
    [id] => 2
    [name] => Beispiel2
    [pri] => 99.00
    [prc_anz] => 1
    [prc_id] => 1
    [prc_name] => test1
    [prc_pri] => 4.99
)

Array
(
    [id] => 2
    [name] => Beispiel2
    [pri] => 99.00
    [prc_anz] => 1
    [prc_id] => 2
    [prc_name] => test2
    [prc_pri] => 5.99
)
usw.

SELECT 
   products.id, 
   products.name, 
   products.pri, 
   COUNT(pr_calc.id) AS prc_anz, 
   GROUP_CONCAT(pr_calc.id SEPARATOR ', ') AS prc_id,
   GROUP_CONCAT(pr_calc.name SEPARATOR ', ') AS prc_name,
   GROUP_CONCAT(pr_calc.pri SEPARATOR ', ') AS prc_pri 
FROM 
   products 
LEFT JOIN 
   pr_calc ON pr_calc.pid = products.id 
GROUP BY 
   products.id, pr_calc.pid 
ORDER BY 
   products.id ASC