这两句查询为什么第一句不能运行,而第二句却能运行?

Question

改成这样吧
SELECT *
  FROM (SELECT   package_id, COUNT (tags) COUNT
            FROM package_items
           WHERE tags LIKE '%HTML%'
        GROUP BY package_id
        ORDER BY COUNT DESC)
 WHERE ROWNUM <= 3

Answer 1

啊，写错了，应该是这样
SELECT *
  FROM PACKAGE
 WHERE package_id IN (
                     SELECT *
                       FROM (SELECT   package_id
                                 FROM package_items
                                WHERE tags LIKE '%HTML%'
                             GROUP BY package_id
                             ORDER BY COUNT (tags) DESC)
                      WHERE ROWNUM <= 3)

Answer 2

再晕，这样不是跟你第二句一样吗....你第一句不行的原因是 order by count(tags) desc在那个in子句里没有意义，oracle认为这样写是错的

Answer 3

select *
 from (
        select * 
         from package 
        where package_id in (
                              select package_id 
                               from (
                                      select package_id 
                                        from package_items 
                                      where tags like '%HTML%' 
                                      group by package_id 
                                      order by count(tags) desc
                                     )                     
                             )
        ) 
where rownum <=3

Answer 4

qiaozhiwei(乔)
的办法可以考虑一下