带有JOIN的DocumentDb SELECT不返回任何内容 [英] DocumentDb SELECT with JOIN not returning anything

问题描述

我在DocumentDb中的文档如下:

My document in DocumentDb looks like this:

{
  "id": 123,
  "timers":
  {
     "projectTimer":
     {
        "id": 234,
        "name": "My Project",
        "startTime": "10:35 AM"
     },
     "taskTimer":
     {
        "id": 789,
        "name": "My Task",
        "startTime": "10:45 AM"
     }
  }
}

这里的关键点是:

• 计时器"是一个对象-不是数组
• 还设置了子对象，即"projectTimer"和"taskTimer"

如果我将SELECT语句设置为以下内容，则可以通过给我同时提供projectTimer和taskTimer子对象来实现

If I set my SELECT statement to the following, it works by giving me both projectTimer and taskTimer sub-objects

SELECT c.timers
FROM Collection c
WHERE c.id = 123

但是以下内容不返回任何内容.我不明白为什么，因为它看起来像是一个非常简单的JOIN:

But the following returns nothing. I don't understand why because it seems like a really simple JOIN:

SELECT t.projectTimer
FROM Collection c
JOIN t IN c.timers
WHERE c.id = 123

知道我在哪里犯错吗?

推荐答案

问题是您正在尝试对非数组对象执行 JOIN .

The issue is that you're trying to do a JOIN on something that's not an array.

相反，如果您稍微修改了文档，则:

If, instead, you reworked your document slightly:

  {
    "id": "123",
    "timers": [
      {
        "projectTimer": {
          "id": 234,
          "name": "My Project",
          "startTime": "10:35 AM"
        }
      },
      {
        "taskTimer": {
          "id": 789,
          "name": "My Task",
          "startTime": "10:45 AM"
        }
      }
    ],
  }

然后您就可以执行 JOIN ，例如:

You'd then be able to do a JOIN like:

select value t
from collection c
join t in c.timers
where c.id = "123"

哪个会返回数组中的每个计时器:

Which would return each of the timers in the array:

[
  {
    "projectTimer": {
      "id": 234,
      "name": "My Project",
      "startTime": "10:35 AM"
    }
  },
  {
    "taskTimer": {
      "id": 789,
      "name": "My Task",
      "startTime": "10:45 AM"
    }
  }
]

请注意在查询中使用 VALUE ，以除去包含的 t 变量.

Note the use of VALUE in the query, to strip away the containing t variable.

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