SELECT c.name AS cname, s.name AS sname,  m.*
            
 FROM `".RA_DB_PREFIX."cat` AS c
 LEFT JOIN `".RA_DB_PREFIX."cat` AS s ON s.parent = c.id
            
 LEFT JOIN `".RA_DB_PREFIX."model` m 
 ON m.`iParentExt` = c.`id` 
            
 GROUP BY m.`iParentExt` 
 ORDER BY m.`idModel` DESC

Array
(
    [0] => Array
        (
            [cname] => Кроссовки
            [sname] => 
            [idShoesModel] => 1
            [iParentExt] => 25
            [iActive] => 1
            [iPrice] => 840
            [iSex] => 1
            [sName] => мод-133
            [sArticle] => 123456
            [sImg] => 
        )
 
    [1] => Array
        (
            [cname] => Зима
            [sname] => Классика
            [idShoesModel] => 
            [iParentExt] => 
            [iActive] => 
            [iPrice] => 
            [iSex] => 
            [sName] => 
            [sArticle] => 
            [sImg] => 
        )
 
)

Array
(
    [0] => Array
        (
            [cname] => Кроссовки
            [sname] => Лето,Спорт
            [idShoesModel] => 1
            [iParentExt] => 25
            [iActive] => 1
            [iPrice] => 840
            [iSex] => 1
            [sName] => мод-133
            [sArticle] => 123456
            [sImg] => 
        )
)

GROUP_CONCAT(s.`name`) AS sname