쿼리문좀 도와주세요

SELECT 
              A.album_name,
              A.reg_no,
              IFNULL(B.album_count, 0) AS count,
         attach_file,
         attach_folder
        FROM album as A
        LEFT OUTER JOIN ( 
                   SELECT 
                 c.album_reg_no,
                 COUNT(*) AS album_count,
                c.attach_file,
                d.attach_folder       
           FROM board_file as c
          LEFT JOIN board AS d ON (c.board_reg_no= d.reg_no AND d.del_yn='N')
          where c.del_yn='N'
             GROUP BY album_reg_no 
           )as B 
           on (A.reg_no = B.album_reg_no)
        WHERE A.code=#{code} AND A.del_yn='N'
        GROUP BY A.album_name
        order by A.reg_date

여기서 board_file 테이블의 album_main_yn의 y값만 나오게하려면 어떻게해야할까요??

도움좀 부탁드립니다