在php mysql中与group by一起计数

Question

Product Table : will display all product - list

prodid |  name   | size
1      |  prd1   |  30
2      |  prd2   |  40
3      |  prd3   |  50
4      |  prod4  |  20

Product Details: - when product list is display , i have text box for each product, where resp. user fill value(500,300..etc) and submit data ..this data is store in product details as below

id | prdid | userid | value |
1  |  1    |  2     |  500
2  |  2    |  2     |  200 
3  |  1    |  3     |  230 
4  |  3    |  2     |  300
5  |  1    |  4     |  100

What i want :

Product Count  |  Product Name  | Product Size 
   3           |    prod1       |   30
   1           |    prod2       |   40
   1           |    prod3       |   50
               |    prod4       |   20

below is list of table :

    $sql = "SELECT * FROM product ";
    $result = $conn->query($sql);

    echo "<table border='1'>
      <tr>
         <th>Product Count</th>
         <th>Product Name</th>
         <th>Product Size</th>
      </tr>";

   while($row = mysqli_fetch_array($result)) {
      echo "<tr>";
      echo "<td>" . ???? . "</td>";
      echo "<td>" . $row['name'] . "</td>";
      echo "<td>" . $row['size'] . "</td>";
      echo "</tr>";
   }
   echo "</table>";

from above i need 2 things: 
1 } product count - count is common 
2 } highlight with red/green that count for resp user who's value is higher for that prdid from product details

ex : in product details :

prdid 1 has 3 count

user for prdid 1 are 3 ( 2,3,4) out of which userid 2 has higher value which is 500 hence only his product column for that prodid will he green else red

hope you guys have understood my requirement....

Answer 1

Hi since your select columns were not in group by clause I think you might have faced some problems. And you have to do left join so that you can get the product details of prd4 which is having count 0 else you wont get that record.

The following query works fine :

SELECT count(pd.prdid) AS productCount, p.name, p.size 
FROM `product` AS p 
LEFT JOIN product_details AS pd ON p.prodid = pd.prdid
GROUP BY p.name,p.size

Answer 2

也许这个查询：

SELECT COUNT(details.*) AS NbProduct, product.name, product.size FROM details JOIN product ON product.id = details.product_id GROUP BY product.name