从 CosmosDB 文档嵌套数组中的对象中选择值

想象一下我们有一个这样的集合（示例取自https://www.documentdb.com/sql/demo https://www.documentdb.com/sql/demo)

{
    "_id" : "19015",
    "description" : "Snacks, granola bars, hard, plain",
    "servings" : [ 
        {
            "amount" : 1,
            "description" : "bar",
            "weightInGrams" : 21
        }, 
        {
            "amount" : 1,
            "description" : "bar (1 oz)",
            "weightInGrams" : 28
        }, 
        {
            "amount" : 1,
            "description" : "bar",
            "weightInGrams" : 25
        }
    ]
}

我如何在 SQL api 中查询 CosmosDB 以获得这样的结果？

{
    "_id" : "19015",
    "servings" : [ 
        {
            "description" : "bar"
        }, 
        {
            "description" : "bar (1 oz)"
        }, 
        {
            "description" : "bar"
        }
    ]
}

在 MongoDB 我会使用这样的查询

db.getCollection('food').find({id: '19015'}, {'servings.description' : 1})

尝试了多种场景的连接等

SELECT 
    food.id,
    food.servings.description
FROM food
WHERE food.id = "19015"

or

SELECT 
    food.id,
    [{
        description: food.servings[0].description
    }] AS servings
FROM food
WHERE food.id = "19015"

• 代替[0]我试过[] or [$]但不起作用

有人知道如何以简单的方式解决这个问题吗？

您可以使用 ARRAY（子查询）表达式来实现此目的。这是查询：

SELECT
    food.id,
    ARRAY(SELECT serving.description FROM serving IN food.servings) AS servings
FROM food
WHERE food.id = "19015"