Come ottenere valori distinti su GROUP_CONCAT utilizzando Google Big Query

Question

Sto cercando di ottenere valori distinti quando utilizzo GROUP_CONCAT in BigQuery.

io ricreare la situazione utilizzando una, ad esempio statica semplice:

EDIT: Ho modificato l'esempio per rappresentare al meglio la mia situazione reale: 2 colonne con group_concat che deve essere distinta:

SELECT 
    category, 
    GROUP_CONCAT(id) as ids, 
    GROUP_CONCAT(product) as products 
FROM 
(SELECT "a" as category, "1" as id, "car" as product), 
(SELECT "a" as category, "2" as id, "car" as product), 
(SELECT "a" as category, "3" as id, "car" as product), 
(SELECT "b" as category, "4" as id, "car" as product), 
(SELECT "b" as category, "5" as id, "car" as product), 
(SELECT "b" as category, "2" as id, "bike" as product), 
(SELECT "a" as category, "1" as id, "truck" as product), 
GROUP BY 
    category 

Questo esempio restituisce:

Row category ids products 
1 a 1,2,3,1 car,car,car,truck 
2 b 4,5,6 car,car,bike 

mi piacerebbe mettere a nudo i valori duplicati trovati, a macerare urna come:

Row category ids products 
1 a 1,2,3 car,truck 
2 b 4,5,6 car,bike 

In MySQL, group_concat ha un'opzione distinti, ma in BigQuery non c'è.

Qualche idea?

Answer 1

Ecco soluzione che utilizza la funzione di aggregazione UNIQUE portata per rimuovere i duplicati. Si noti, che al fine di usarlo, prima abbiamo bisogno di costruire un REPEATED utilizzando NEST aggregazione:

SELECT 
    GROUP_CONCAT(UNIQUE(ids)) WITHIN RECORD, 
    GROUP_CONCAT(UNIQUE(products)) WITHIN RECORD 
FROM (
SELECT 
    category, 
    NEST(id) as ids, 
    NEST(product) as products 
FROM 
(SELECT "a" as category, "1" as id, "car" as product), 
(SELECT "a" as category, "2" as id, "car" as product), 
(SELECT "a" as category, "3" as id, "car" as product), 
(SELECT "b" as category, "4" as id, "car" as product), 
(SELECT "b" as category, "5" as id, "car" as product), 
(SELECT "b" as category, "2" as id, "bike" as product), 
(SELECT "a" as category, "1" as id, "truck" as product), 
GROUP BY 
    category 
) 

Answer 2

rimozione dei duplicati prima di applicare group_concat otterrà il risultato desiderato:

SELECT 
     category, 
     GROUP_CONCAT(id) as ids 
    FROM ( 
    SELECT category, id 
    FROM 
    (SELECT "a" as category, "1" as id), 
    (SELECT "a" as category, "2" as id), 
    (SELECT "a" as category, "3" as id), 
    (SELECT "b" as category, "4" as id), 
    (SELECT "b" as category, "5" as id), 
    (SELECT "b" as category, "6" as id), 
    (SELECT "a" as category, "1" as id), 
    GROUP BY 
     category, id 
    ) 
    GROUP BY 
     category