在某些版本的Oracle中,是否存在相关子查询的嵌套限制?

以下代码将帮助您理解我的问题:

create table con ( content_id number);
create table mat ( material_id number, content_id number, resolution number, file_location varchar2(50));
create table con_groups (content_group_id number, content_id number);

insert into con values (99);
insert into mat values (1, 99, 7, 'C:\foo.jpg');
insert into mat values (2, 99, 2, '\\server\xyz.mov');
insert into mat values (3, 99, 5, '\\server2\xyz.wav');
insert into con values (100);
insert into mat values (4, 100, 5, 'C:\bar.png');
insert into mat values (5, 100, 3, '\\server\xyz.mov');
insert into mat values (6, 100, 7, '\\server2\xyz.wav');

insert into con_groups values (10, 99);
insert into con_groups values (10, 100);

commit;

SELECT m.material_id,
       (SELECT file_location 
          FROM (SELECT file_location
                  FROM mat
                 WHERE mat.content_id = m.content_id
              ORDER BY resolution DESC) special_mats_for_this_content            
         WHERE rownum = 1) special_mat_file_location                                     
  FROM mat m
 WHERE m.material_id IN (select material_id 
                           from mat
                     inner join con on con.content_id = mat.content_id
                     inner join con_groups on con_groups.content_id = con.content_id
                          where con_groups.content_group_id = 10);

请将查询末尾的数字10视为参数。换句话说,在这个例子中,这个值只是硬编码的;它会根据输入而改变。

我的问题是:为什么我会出错

"M"."CONTENT_ID": invalid identifier 

对于嵌套的相关子查询?有某种筑巢限制吗?需要为结果集中的每一行运行此子查询,因为结果将根据内容\u id而更改,每一行的内容\u id可能不同。我如何用Oracle来完成这个任务?

我不是要开始讨论SQL Server与Oracle之间的关系,但我来自SQL Server的背景,我想指出以下等效查询在SQL Server上运行良好:

create table con ( content_id int);
create table mat ( material_id int, content_id int, resolution int, file_location varchar(50));
create table con_groups (content_group_id int, content_id int);

insert into con values (99);
insert into mat values (1, 99, 7, 'C:\foo.jpg');
insert into mat values (2, 99, 2, '\\server\xyz.mov');
insert into mat values (3, 99, 5, '\\server2\xyz.wav');
insert into con values (100);
insert into mat values (4, 100, 5, 'C:\bar.png');
insert into mat values (5, 100, 3, '\\server\xyz.mov');
insert into mat values (6, 100, 7, '\\server2\xyz.wav');

insert into con_groups values (10, 99);
insert into con_groups values (10, 100);

SELECT m.material_id,
       (SELECT file_location 
          FROM (SELECT TOP 1 file_location
                  FROM mat
                 WHERE mat.content_id = m.content_id
              ORDER BY resolution DESC) special_mats_for_this_content            
               ) special_mat_file_location                                     
  FROM mat m
 WHERE m.material_id IN (select material_id 
                           from mat
                     inner join con on con.content_id = mat.content_id
                     inner join con_groups on con_groups.content_id = con.content_id
                          where con_groups.content_group_id = 10);

您能帮助我理解为什么我可以在SQL Server而不是Oracle 9i中这样做吗?如果存在嵌套限制,那么如何在Oracle中的单个select查询中完成此操作,而不使用循环表和/或临时表?