选择内部联接，sql和php的group_concat

Question

I have the following query:

$myquery = mysql_query("SELECT p.name, GROUP_CONCAT(m.name) as products
                    FROM access as pm
                    INNER JOIN seller as p on p.id = pm.id_seller
                    INNER JOIN products as m on m.id  = pm.id_product
                    WHERE p.id = '".$_COOKIE['id_seller']."'");

Which returns me this array:

Array (
[0] => Seller Name [name] => Seller Name
[1] => Product1 [products] => Product1
);

How should I query the database correctly? Thanking in consideration that I have 3 tables (products, access and seller). What I'd like to achieve is to attribute (access) one or more products to a seller.

And how my drop-down list populate code would look like?

<?php
      echo'<select name="productaccess">';
foreach($myquery as $product) {
      echo'<option value="'.$product.'">'.$product.'</option>';
}
      echo'</select>';
?> 

Thanks!

Answer 1

If you want the products for just one seller, you don't need grouping at all. Just list the names of the products:

$myquery = mysql_query("SELECT m.name
                    FROM access as pm
                    INNER JOIN seller as p on p.id = pm.id_seller
                    INNER JOIN products as m on m.id  = pm.id_product
                    WHERE p.id = '".$_COOKIE['id_seller']."'");

Now $myquery is only a resource identifier, not the results, so you get the latter with mysql_fetch_array() like this:

while($row=mysql_fetch_array($myquery)) {
    echo'<option value="'.$row['name'].'">'.$row['name'].'</option>';
}

Answer 2

GROUP_CONCAT is used with a GROUP BY clause, which is not present. Add a 'GROUP BY p.name' to your SQL. That will make the above SQL return a single row, with the seller name and the product names, separated by commas. Then burst the product names into an array, which you then feed to the foreach loop.