DocumentDB SQL - 数组创建

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在DocumentDB SQL中，微软添加了一个关键功能，借助它我们可以轻松创建数组。这意味着当我们运行查询时，它会创建一个类似于 JSON 对象的集合数组作为查询结果。

让我们考虑与前面示例中相同的文档。

以下是AndersenFamily文档。

{ 
   "id": "AndersenFamily", 
   "lastName": "Andersen",
	
   "parents": [ 
      { "firstName": "Thomas", "relationship":  "father" }, 
      { "firstName": "Mary Kay", "relationship":  "mother" } 
   ], 
   
   "children": [ 
      { 
         "firstName": "Henriette Thaulow", 
         "gender": "female", 
         "grade": 5, 
         "pets": [ { "givenName": "Fluffy", "type":  "Rabbit" } ] 
      } 
   ],
   
   "location": { "state": "WA", "county": "King", "city": "Seattle" }, 
   "isRegistered": true 
} 

以下是史密斯家族的文件。

{ 
   "id": "SmithFamily", 
	
   "parents": [ 
      { "familyName": "Smith", "givenName": "James" }, 
      { "familyName": "Curtis", "givenName": "Helen" } 
   ],
   
   "children": [ 
      {
         "givenName": "Michelle", 
         "gender": "female", 
         "grade": 1 
      },
		
      { 
         "givenName": "John", 
         "gender": "male", 
         "grade": 7,
			
         "pets": [ 
            { "givenName": "Tweetie", "type": "Bird" } 
         ] 
      } 
   ], 
   
   "location": { 
      "state": "NY", 
      "county": "Queens", 
      "city": "Forest Hills" 
   },
   
   "isRegistered": true 
}

以下是WakefieldFamily文档。

{ 
   "id": "WakefieldFamily", 
	
   "parents": [ 
      { "familyName": "Wakefield", "givenName": "Robin" }, 
      { "familyName": "Miller", "givenName": "Ben" } 
   ],
   
   "children": [ 
      { 
         "familyName": "Merriam", 
         "givenName": "Jesse", 
         "gender": "female", 
         "grade": 6,
			
         "pets": [ 
            { "givenName": "Charlie Brown", "type": "Dog" }, 
            { "givenName": "Tiger", "type": "Cat" }, 
            { "givenName": "Princess", "type": "Cat" }
         ]
      },
		
      { 
         "familyName": "Miller", 
         "givenName": "Lisa", 
         "gender": "female", 
         "grade": 3,
			
         "pets": [ 
            { "givenName": "Jake", "type": "Snake" } 
         ] 
      } 
   ], 
   
   "location": { "state": "NY", "county": "Manhattan", "city": "NY" }, 
   "isRegistered": false 
}

让我们看一个例子。

以下查询将返回每个家庭的姓氏和地址。

SELECT f.id AS FamilyName, 
[f.location.city, f.location.county, f.location.state] AS Address 
FROM Families f

可以看到，城市、县和州字段括在方括号中，这将创建一个数组，该数组名为“Address”。执行上述查询时，会产生以下输出。

[ 
   { 
      "FamilyName": "WakefieldFamily", 
      "Address": [ 
         "NY", 
         "Manhattan", 
         "NY" 
      ] 
   },
	
   { 
      "FamilyName": "SmithFamily", 
      "Address": [
         "Forest Hills", 
         "Queens", 
         "NY" 
      ] 
   },
	
   { 
      "FamilyName": "AndersenFamily", 
      "Address": [ 
         "Seattle", 
         "King", 
         "WA" 
      ] 
   } 
]

城市、县和州信息将添加到上述输出的地址数组中。