Sql query - Cant select the max value of a row - mysql

Question

I have this query that showing items in my site.
$sql = "
select p.id
, p.name
, p.logo
, p.short_description
, c.Parent_category
, IF(d.commission_name = 'percent'
, CONCAT(FORMAT(d.action, 2)/2 ,' %')
, CONCAT(FORMAT(d.action,2)/2,' €')) as comms
, GROUP_CONCAT(c.category_name SEPARATOR ',') as category_names
from eshop p
join eshop_cat c
on p.id = c.eshop_id
join eshop_commissions d
on p.id = d.eshop_id
where c.Parent_category = 'fashion'
and p.sites = 1
GROUP
BY d.action DESC
";
The problem is here
IF(d.commission_name = 'percent', CONCAT(FORMAT(d.action, 2)/2 ,' %') ,
CONCAT(FORMAT(d.action,2)/2,' €'))
i need only the biggest value of each eshop id. i tryied with this
IF(d.commission_name = 'percent', CONCAT(FORMAT(max(d.action), 2)/2 ,' %') ,
CONCAT(FORMAT(max(d.action),2)/2,' €'))
but its not working
For example i have 2 entries with the same eshop id
How can i receive only 1 commission that will be the biggest?
eshop_id commission_name action
1 percent 20 (%)
1 fixed_amount 30 (euro)
EDITED
CREATE TABLE `eshop` (
`id` int(11) NOT NULL,
`name` text NOT NULL,
`logo` text NOT NULL,
`short_description` text NOT NULL,
`sites` tinyint(1) NOT NULL,
`url` text NOT NULL,
`timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`summary` text NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `eshop_commissions` (
`commission_name` text NOT NULL,
`eshop_id` int(11) NOT NULL,
`action` decimal(10,2) NOT NULL,
`subaction` decimal(10,2) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `eshop_cat` (
`eshop_id` int(11) NOT NULL,
`category_name` text NOT NULL,
`Parent_category` text
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `eshop_commissions` (`commission_name`, `eshop_id`, `action`, `subaction`) VALUES
('percent', 100, '12.00', '12.00'),
('fixed_amount', 100, '15.00', '15.00'),
('percent', 100, '5.00', '5.00'),
('percent', 100, '2.00', '2.00');
INSERT INTO `eshop` (`id`, `name`, `logo`, `short_description`, `description`, `sites`, `url, `timestamp`, `summary`) VALUES
(100, 'Tokotoukan', 'logo-tokotoukan.gif', '<p>\r\n !</p>\r\n', '<p>\r\n <font face=\"arial\" size=\"2\">Τo TOKOTOUKAN </font></p>\r\n', 1, 'http://www.com', ''2017-07-07 17:39:59', '15,00%');
INSERT INTO `eshop_cat` (`eshop_id`, `category_name`, `Parent_category`) VALUES
(100, 'fashion', 'fashion');