N1QL Concatenate many children rows into single string

问题

Consider in Couchbase I have a person database, with 3 documents:

Person A
    Child AA
        Grand AAA
        Grand AAB
    Child AB
        Grand ABA
        Grand ABB

Person B

Person C
    Child CA
    Child CB
        Grand CBA

Is there an easy way to turn this into following results using N1QL? I am trying to display each person with their grand children displayed into strings?

Person A, Grand: "AAA, AAB, ABA, ABB"
Person B, Grand: ""
Person C, Grand: "CBA"

回答1:

You can do the following:

SELECT p.name AS p, ENCODE_JSON(ARRAY_AGG(g.name)) AS g
FROM person AS p LEFT OUTER UNNEST p.child AS c LEFT OUTER UNNEST c.grand AS g
GROUP BY p;

来源：https://stackoverflow.com/questions/35742657/n1ql-concatenate-many-children-rows-into-single-string