Couchbase N1QL 查询对象数组中的 select 值

Question

从对象数组中 select 取值的正确方法是什么？

想要检索不同的评论列表。

[
  "comment 1",
  "comment 2",
  "comment 3",
  "comment 4"
]

当前 N1QL 查询

SELECT links[*].comment FROM `my-db`
WHERE type = "links" AND ANY l IN links SATISFIES l.comment IS NOT MISSING END

结果

[
  {
    "comment": [
      "comment 1"
    ]
  },
  {
    "comment": [
      "comment 1",
      "comment 2"
    ]
  },
  {
    "comment": [
      "comment 3",
      "comment 4"
    ]
  }
]

给定一系列包含评论字段的文档：

{
  "type": "links",
  "links": [
    {
      "comment": "comment 1"
    }
  ]
}

{
  "type": "links",
  "links": [
    {
      "comment": "comment 1"
    },
    {
      "comment": "comment 2"
    }
  ]
}

{
  "type": "links",
  "links": [
    {
      "comment": "comment 3"
    },
    {
      "comment": "comment 4"
    }
  ]
}

Answer 1

使用 UNNEST

SELECT DISTINCT RAW l.comment 
FROM `my-db` AS m
UNNEST m.links AS l
WHERE m.type = "links" AND l.comment IS NOT NULL;

或

If data set is not too large.

SELECT RAW  ARRAY_DISTINCT(ARRAY_FLATTEN(ARRAY_AGG(m.links[*].comment) ,2))
FROM `my-db` AS m
WHERE m.type = "links";

Couchbase N1QL 查询对象数组中的 select 值

Couchbase N1QL query to select value from object array

couchbase

n1ql