精品查询（sql语句）

1、表字段
   1）t_comment表
         
   2）t_books表
        
2、sql语句

    SELECT *
    FROM t_books
    WHERE BOOKID IN(
        SELECT BOOKID
        FROM(
            SELECT BOOKID, (SUM(CASE commtype WHEN 1 THEN 1 ELSE 0 END)- SUM(CASE commtype WHEN 2 THEN 1 ELSE 0 END)) AS num
            FROM t_comment
            GROUP BY BOOKID
            ORDER BY num DESC
            LIMIT 4) as tt2)