关于 无法绑定由多个部分组成的标识符 ，求解答

select b.isum,a.* from B_YDMNG_ProductExploit a inner join (select count(1) as isum from P_Trade_His b where b.AllGoodsDetail like '%'+a.productSku+'%') b on a.status=3

[Err] 42000 - [SQL Server]无法绑定由多个部分组成的标识符 "a.productSku"。

    SELECT b.isum,
           a.*
      FROM b_ydmng_productexploit a
INNER JOIN (
                SELECT a1.productsku,
                       COUNT(1) AS isum
                  FROM b_ydmng_productexploit a1
                  JOIN p_trade_his b1
                    ON b1.allgoodsdetail LIKE '%'+a1.productsku+'%'
                 WHERE a1.status = 3
              GROUP BY a1.productsku
           ) b
        ON a.productsku = b.productsku
     WHERE a.status = 3