MongoDB中数组的$ lte：10和$ not：{$ gt：10}的区别？

Question

我们可以看到，当使用“grades.score”：{$ lte：10}时，大于10的值也会出现在grades数组中。但是当使用“scores.score”：{$ not：{$ gt：10}}时，它们会被过滤掉。 尽管两者的含义都相同。

这里是集即样品 “餐馆”：

{ 
    "address": { 
    "building": "1007", 
    "coord": [ -73.856077, 40.848447 ], 
    "street": "Morris Park Ave", 
    "zipcode": "10462" 
    }, 
    "borough": "Bronx", 
    "cuisine": "Bakery", 
    "grades": [ 
    { "grade": "A", "score": 2 }, 
    { "grade": "A", "score": 6 }, 
    { "grade": "A", "score": 10 }, 
    { "grade": "A", "score": 9 }, 
    { "grade": "B", "score": 14 } 
    ], 
    "name": "Morris Park Bake Shop", 
    "restaurant_id": "30075445" 
} 

这是第一次查询：

db.restaurants.find({"grades.score":{$lte:10}},{"grades.score":1,name:1,restau rant_id:1,borough:1,cuisine:1,_id:0}).pretty()

结果：

{ 
    "borough" : "Queens", 
    "cuisine" : "Ice Cream, Gelato, Yogurt, Ices", 
    "grades" : [ 
      { 
        "score" : 9 
      }, 
      { 
        "score" : 10 
      }, 
      { 
        "score" : 13 
      } 
    ], 
    "name" : "Carvel Ice Cream", 
    "restaurant_id" : "40361322" 
} 
{ 
    "borough" : "Brooklyn", 
    "cuisine" : "Delicatessen", 
    "grades" : [ 
      { 
        "score" : 4 
      }, 
      { 
        "score" : 3 
      }, 
      { 
        "score" : 10 
      } 
    ], 
    "name" : "Nordic Delicacies", 
    "restaurant_id" : "40361390" 
} 
{ 
    "borough" : "Manhattan", 
    "cuisine" : "American ", 
    "grades" : [ 
      { 
        "score" : 12 
      }, 
      { 
        "score" : 16 
      }, 
      { 
        "score" : 9 
      }, 
      { 
        "score" : 13 
      }, 
      { 
        "score" : 11 
      } 
    ], 
    "name" : "Glorious Food", 
    "restaurant_id" : "40361521" 
} 
{ 
    "borough" : "Brooklyn", 
    "cuisine" : "American ", 
    "grades" : [ 
      { 
        "score" : 11 
      }, 
      { 
        "score" : 2 
      }, 
      { 
        "score" : 13 
      }, 
      { 
        "score" : 11 
      } 
    ], 
    "name" : "The Movable Feast", 
    "restaurant_id" : "40361606" 
} 
{ 
    "borough" : "Queens", 
    "cuisine" : "Delicatessen", 
    "grades" : [ 
      { 
        "score" : 12 
      }, 
      { 
        "score" : 9 
      }, 
      { 
        "score" : 7 
      }, 
      { 
        "score" : 10 
      } 
    ], 
    "name" : "Sal'S Deli", 
    "restaurant_id" : "40361618" 
} 

这里是第二个查询：

db.restaurants.find({"grades.score":{$not:{$gt:10}}}, {"grades.score":1,name:1,restaurant_id:1,borough:1,cuisine:1,_id:0}).pretty()

结果：

{ 
    "borough" : "Bronx", 
    "cuisine" : "American ", 
    "grades" : [ 
      { 
        "score" : 5 
      }, 
      { 
        "score" : 3 
      }, 
      { 
        "score" : 4 
      }, 
      { 
        "score" : 9 
      } 
    ], 
    "name" : "African Market (Baboon Cafe)", 
    "restaurant_id" : "40368026" 
} 
{ 
    "borough" : "Staten Island", 
    "cuisine" : "Italian", 
    "grades" : [ 
      { 
        "score" : 10 
      }, 
      { 
        "score" : 3 
      }, 
      { 
        "score" : 6 
      }, 
      { 
        "score" : 10 
      } 
    ], 
    "name" : "Roadhouse Restaurant", 
    "restaurant_id" : "40368034" 
} 
{ 
    "borough" : "Manhattan", 
    "cuisine" : "French", 
    "grades" : [ 
      { 
        "score" : 9 
      }, 
      { 
        "score" : 2 
      }, 
      { 
        "score" : 8 
      } 
    ], 
    "name" : "Pergola Des Artistes", 
    "restaurant_id" : "40369139" 
} 
{ 
    "borough" : "Brooklyn", 
    "cuisine" : "Hamburgers", 
    "grades" : [ 
      { 
        "score" : 10 
      }, 
      { 
        "score" : 7 
      }, 
      { 
        "score" : 5 
      }, 
      { 
        "score" : 10 
      } 
    ], 
    "name" : "Mcdonald'S", 
    "restaurant_id" : "40369535" 
} 
{ 
    "borough" : "Brooklyn", 
    "cuisine" : "American ", 
    "grades" : [ 
      { 
        "score" : 10 
      }, 
      { 
        "score" : 8 
      } 
    ], 
    "name" : "The River Cafe", 
    "restaurant_id" : "40369608" 
} 

Answer 1

您的查询既不实际筛选项目出grades阵列。

Query a Field that Contains an Array

如果字段中包含的阵列，并且查询具有多个条件运算符，就好像是单个阵列元件满足条件或阵列的组合的整个将匹配字段元素符合条件。

你的第一查询时，

db.restaurants.find({"grades.score":{$lte:10}},{"grades.score":1,name:1,restaurant_id:1,borough:1, cuisine:1,_id:0}).pretty() 

返回包含的grades阵列，其具有小于或等于10。

你的第二查询score值中的至少一个项目的文件，

db.restaurants.find({"grades.score":{$not:{$gt:10}}},{"grades.score":1,name:1,restaurant_id:1,borough:1,cuisine:1,_id:0}).pretty() 

return doc在grades阵列中没有任何项目，其score值大于10.

我假设您打算这么做，在此SO answer中进行了描述。