ORACLEで文字列結合について

WITH 取り扱いVIEW(お店ID, 店名, 取り扱い商品)

AS (

SELECT

      S1.お店ID

    , S1.店名

    , CAST(P1.商品名 AS varchar) AS 取り扱い商品 

FROM お店 AS S1

INNER JOIN 取り扱い AS L1

    ON L1.お店ID = S1.お店ID

INNER JOIN 商品 AS P1

    ON P1.商品ID = L1.商品ID

UNION ALL

SELECT

      S2.お店ID

    , S2.店名

    , CAST(取り扱いVIEW.取り扱い商品 + ',' + P2.商品名 AS varchar) AS 取り扱い商品 

FROM お店 AS S2

INNER JOIN 取り扱いVIEW 

    ON 取り扱いVIEW.お店ID = S2.お店ID

INNER JOIN 取り扱い AS L2

    ON L2.お店ID = S2.お店ID

INNER JOIN 商品 AS P2

    ON P2.商品ID = L2.商品ID

       AND 取り扱いVIEW.取り扱い商品 NOT LIKE '%' + P2.商品名 + '%'

)



SELECT * FROM 取り扱いVIEW AS LOB

WHERE LOB.取り扱い商品

        = (SELECT TOP 1 取り扱い商品

           FROM 取り扱いVIEW

           WHERE お店ID = LOB.お店ID

           ORDER BY 取り扱い商品 DESC)

ORDER BY お店ID