MongoDB 数组

---

数据准备

{
        "_id" : ObjectId("59982b08b8f62e79cdc29da2"),
        "name" : "lily",
        "age" : 12
}
{ "_id" : ObjectId("5999ebe32af74d2adccf516a"), "name" : "t", "age" : 13 }
{
        "_id" : ObjectId("599ac13091cf72aa04177629"),
        "name" : "xiaowang",
        "age" : 16,
        "habbit" : [
                "banana",
                "apple",
                "peach"
        ],
        "score" : [
                51,
                62
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762a"),
        "name" : "xiaoli",
        "age" : 17,
        "habbit" : [
                "apple",
                "peach"
        ],
        "score" : [
                73,
                23
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762b"),
        "name" : "xiaoming",
        "age" : 16,
        "habbit" : [
                "banana",
                "apple",
                "peach",
                "grape"
        ],
        "score" : [
                83,
                97
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762c"),
        "name" : "xiaohong",
        "age" : 17,
        "habbit" : [
                "banana",
                "grape",
                "tomato"
        ],
        "score" : [
                87,
                83
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762d"),
        "name" : "xiaofang",
        "age" : 18,
        "habbit" : [
                "peach",
                "grape"
        ],
        "score" : [
                54,
                67
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762e"),
        "name" : "xiaoqiu",
        "age" : 17,
        "habbit" : [
                "potato",
                "tomato"
        ],
        "score" : [
                91,
                82
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762f"),
        "name" : "xiaozhang",
        "age" : 19,
        "habbit" : [
                "peach",
                "grape"
        ],
        "score" : [
                79,
                83
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa04177630"),
        "name" : "xiaowang",
        "age" : 16,
        "habbit" : [
                "banana",
                "apple",
                "peach"
        ],
        "score" : [
                87,
                89
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa04177631"),
        "name" : "xiaoli",
        "age" : 17,
        "habbit" : [
                "apple",
                "peach"
        ],
        "score" : [
                93,
                95
        ]
}

1.全文匹配$all

db.userlist.find({habbit:{$all:['grape','peach']}}).pretty()#habbit包含peach和grape的

{
        "_id" : ObjectId("599ac13091cf72aa0417762b"),
        "name" : "xiaoming",
        "age" : 16,
        "habbit" : [
                "banana",
                "apple",
                "peach",
                "grape"
        ],
        "score" : [
                83,
                97
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762d"),
        "name" : "xiaofang",
        "age" : 18,
        "habbit" : [
                "peach",
                "grape"
        ],
        "score" : [
                54,
                67
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762f"),
        "name" : "xiaozhang",
        "age" : 19,
        "habbit" : [
                "peach",
                "grape"
        ],
        "score" : [
                79,
                83
        ]
}

2.符号运算(>=<)

下边的文档查询的例子是查询score元素：一个元素可以满足>70,另一个元素<90,或者是一个元素可以同时满足这两个条件。
db.userlist.find({score:{$gt:70,$lt:99}})

3. 元素存在$exists

• 某属性是否存在$exists
  db.userlist.find({habbit:{$exists:true}})#查询userlist中有habbit元素的所有文档
  db.userlist.find({habbit:{$exists:false}})#查询userlist中没有habbit元素的所有文档

4. 根据元素的个数查询

db.userlist.find({habbit:{$size:3}})#查询有3个habbit的人
显示结果：

{
        "_id" : ObjectId("599ac13091cf72aa04177629"),
        "name" : "xiaowang",
        "age" : 16,
        "habbit" : [
                "banana",
                "apple",
                "peach"
        ],
        "score" : [
                51,
                62
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762c"),
        "name" : "xiaohong",
        "age" : 17,
        "habbit" : [
                "banana",
                "grape",
                "tomato"
        ],
        "score" : [
                87,
                83
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa04177630"),
        "name" : "xiaowang",
        "age" : 16,
        "habbit" : [
                "banana",
                "apple",
                "peach"
        ],
        "score" : [
                87,
                89
        ]
}

5.数组中指定下标

db.userlist.find({'habbit.2':'peach'})#寻找habbit下标2为peach的元素。

{
        "_id" : ObjectId("599ac13091cf72aa04177629"),
        "name" : "xiaowang",
        "age" : 16,
        "habbit" : [
                "banana",
                "apple",
                "peach"
        ],
        "score" : [
                51,
                62
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa0417762b"),
        "name" : "xiaoming",
        "age" : 16,
        "habbit" : [
                "banana",
                "apple",
                "peach",
                "grape"
        ],
        "score" : [
                83,
                97
        ]
}
{
        "_id" : ObjectId("599ac13091cf72aa04177630"),
        "name" : "xiaowang",
        "age" : 16,
        "habbit" : [
                "banana",
                "apple",
                "peach"
        ],
        "score" : [
                87,
                89
        ]
}

6.元素匹配$elemMatch

数据准备：

> db.inventory.insertMany( [
...    { item: "journal", instock: [ { warehouse: "A", qty: 5 }, { warehouse: "C", qty: 15 } ] },
...    { item: "notebook", instock: [ { warehouse: "C", qty: 5 } ] },
...    { item: "paper", instock: [ { warehouse: "A", qty: 60 }, { warehouse: "B", qty: 15 } ] },
...    { item: "planner", instock: [ { warehouse: "A", qty: 40 }, { warehouse: "B", qty: 5 } ] },
...    { item: "postcard", instock: [ { warehouse: "B", qty: 15 }, { warehouse: "C", qty: 35 } ] }
... ]);

查询stock中warehouse=C的元素：
db.inventory.find({'instock':{$elemMatch:{warehouse:'C'}}})

{ "_id" : ObjectId("599af38691cf72aa04177632"), "item" : "journal", "instock" : [ { "warehouse" : "A", "qty" : 5 }, { "warehouse" : "C", "qty" : 15 } ] }
{ "_id" : ObjectId("599af38691cf72aa04177633"), "item" : "notebook", "instock" : [ { "warehouse" : "C", "qty" : 5 } ] }
{ "_id" : ObjectId("599af38691cf72aa04177636"), "item" : "postcard", "instock" : [ { "warehouse" : "B", "qty" : 15 }, { "warehouse" : "C", "qty" : 35 } ] }

7.$where

db.userlist.find({$where:'this.age<17'})