从SQL查询中获取一列中的多个值

Question

我有3个表。

A表：

id_a | description 
------------------- 
    1 |  X 
    2 |  Y   
    3 |  Z 
    4 |  H 

B表：

id_b | description 
------------------- 
    1 |  J 
    2 |  K   
    3 |  W 

C表：

id_c | idex_a | idex_b | quantity 
---------------------------------- 
    1 | 1 | 1 | 10 
    2 | 1 | 2 | 32 
    3 | 2 | 3 | 41 
    4 | 1 | 3 | 10 
    5 | 3 | 2 | 24 
    6 | 3 | 3 | 26 

我怎样才能获得这样的结果？

A.id_a | A.description | All B.description, B.quantity IN C WHITH A.id_a = C.idex_a 
    1 |  X  | J[10], K[32], W[10] 
    2 |  Y  | W[41] 
    3 |  Z  | K[24], W[26] 
    4 |  H  | 

Answer 1

你可以尝试以下方法：

select a.id_a 
     , a.description 
     , coalesce(group_concat(distinct concat(b.description, '[', c.quantity, ']') order by b.id_b separator ', ') 
       , '') 
from a 
left join c on a.id_a = c.idex_a 
left join b on b.id_b = c.idex_b 
group by a.id_a 
     , a.description 

SQLFiddle