$searchCondition['where'] .= ' AND alldtl.product_id NOT IN(
    SELECT 
        product_id 
    FROM 
        dtb_products
    WHERE 
        alldtl.product_id < (
            SELECT 
                MAX(p2.product_id) 
            FROM 
                (
                    SELECT 
                        DISTINCT sub_title1, product_id 
                    FROM 
                        dtb_products 
                ) AS p2
            WHERE
                alldtl.sub_title1 = p2.sub_title1
        )
)';