Các hàm tổng hợp do người dùng định nghĩa trong mệnh đề Oracle PIVOT

Question

Không thể sử dụng các hàm tổng hợp do người dùng định nghĩa trong mệnh đề Oracle PIVOT.

Tôi đã tạo hàm tổng hợp do người dùng xác định được gọi là string_agg.
tôi có thể sử dụng nó trong một tuyên bố đơn giản như ...

select id, string_agg(value) from 
(
    select 'user1' as id, 'BMW' as value, 'CAR'  as type from dual union 
    select 'user1' as id, 'Audi' as value, 'CAR'  as type from dual union 
    select 'user2' as id, 'Honda' as value, 'CAR'  as type from dual union 
    select 'user1' as id, 'Dell' as value, 'COMPUTER' as type from dual union 
    select 'user1' as id, 'Sony' as value, 'COMPUTER' as type from dual union 
    select 'user2' as id, 'HP' as value, 'COMPUTER' as type from dual 
) 
group by id, type

Kết quả trong:

ID TYPE STRING_AGG(VALUE) 
user1  CAR    Audi,BMW 
user1  COMPUTER  Dell,Sony 
user2  CAR    Honda 
user2  COMPUTER  HP 

Tuy nhiên khi tôi cố gắng sử dụng các chức năng tương tự trong một điều khoản trục

select * from 
( 
    select id, type, string_agg(value) as value from 
    (
     select 'user1' as id, 'BMW' as value, 'CAR'  as type from dual union 
     select 'user1' as id, 'Audi' as value, 'CAR'  as type from dual union 
     select 'user2' as id, 'Honda' as value, 'CAR'  as type from dual union 
     select 'user1' as id, 'Dell' as value, 'COMPUTER' as type from dual union 
     select 'user1' as id, 'Sony' as value, 'COMPUTER' as type from dual union 
     select 'user2' as id, 'HP' as value, 'COMPUTER' as type from dual 
    ) 
    group by id, type 
) 
PIVOT (string_agg(value) FOR id IN ('user1' user1, 'user2' user2));

tôi nhận được như sau lỗi ...

ORA-56902: expect aggregate function inside pivot operation

Dự kiến ​​ kết quả là ...

TYPE USER1 USER2 
COMPUTER Dell,Sony HP  
CAR   Audi,BMW Honda

Answer 1

Pivot không phải qua hàm tổng hợp tương tự:

select * from 
( 
    select id, type, LISTAGG(value) WITHIN GROUP (ORDER BY 1) as value from 
    (
     select 'user1' as id, 'BMW' as value, 'CAR'  as type from dual union 
     select 'user1' as id, 'Audi' as value, 'CAR'  as type from dual union 
     select 'user2' as id, 'Honda' as value, 'CAR'  as type from dual union 
     select 'user1' as id, 'Dell' as value, 'COMPUTER' as type from dual union 
     select 'user1' as id, 'Sony' as value, 'COMPUTER' as type from dual union 
     select 'user2' as id, 'HP' as value, 'COMPUTER' as type from dual 
    ) 
    group by id, type 
) 
PIVOT (max(value) FOR id IN ('user1' user1, 'user2' user2)); 

Answer 2

gì về việc cố gắng wmsys.wm_concat thay vì tổng hợp người dùng định nghĩa của bạn?