mongoDB 查询结果

Question

我正在学习 mongodb.I 有一份如下所示的文档：

{
"_id" : ObjectId("558bb3490e98e0108940afee"),
"term" : "nike team court graphic  mens tennis  crew and shorts",
"year" : "2015",
"month" : "06",
"day" : "06",
"hour" : "12",
"count" : 15
}
{
"_id" : ObjectId("558bb3500e98e0108940afef"),
"term" : "nike team court graphic  mens tennis  crew and shorts",
"year" : "2015",
"month" : "06",
"day" : "06",
"hour" : "12",
"count" : 12
}
{
"_id" : ObjectId("558bb3550e98e0108940aff0"),
"term" : "nike team court graphic  mens tennis  crew and shorts",
"year" : "2015",
"month" : "06",
"day" : "06",
"hour" : "12",
"count" : 18
}
{
"_id" : ObjectId("558bb3640e98e0108940aff1"),
"term" : "nike",
"year" : "2015",
"month" : "06",
"day" : "06",
"hour" : "12",
"count" : 18
}
{
"_id" : ObjectId("558bb3680e98e0108940aff2"),
"term" : "nike",
"year" : "2015",
"month" : "06",
"day" : "06",
"hour" : "12",
"count" : 12
 }
 {
"_id" : ObjectId("558bb36b0e98e0108940aff3"),
"term" : "nike",
"year" : "2015",
"month" : "06",
"day" : "06",
"hour" : "12",
"count" : 13
}
{
"_id" : ObjectId("558bb3720e98e0108940aff4"),
"term" : "nike",
"year" : "2015",
"month" : "06",
"day" : "06",
"hour" : "12",
"count" : 10
}
{
"_id" : ObjectId("558bb3790e98e0108940aff5"),
"term" : "nike1",
"year" : "2015",
"month" : "06",
"day" : "06",
"hour" : "12",
"count" : 10
}
{
"_id" : ObjectId("558bb37e0e98e0108940aff6"),
"term" : "nike1",
"year" : "2015",
"month" : "06",
"day" : "06",
"hour" : "12",
"count" : 111
}
{
    "term" : "nike1",
    "year" : "2014",
    "month" : "03",
    "day" : "07",
    "count" : 110
}

我想以 returns term , year , month , day and sum of total count based on the match of term,year,month and day.

我的查询

db.products.group( {
$match:{$and:[{year:"2015"},{month:"06"},{day:"06"}]},
key: {  term: "$term", year: "2015", month : "06", day : "06" },
reduce: function(cur, result) { result.count += cur.count },
initial: { count: 0 }
} )

我得到的输出：

[

{
    "term" : "nike team court graphic  mens tennis  crew and shorts",
    "year" : "2015",
    "month" : "06",
    "day" : "06",
    "count" : 45
},
{
    "term" : "nike",
    "year" : "2015",
    "month" : "06",
    "day" : "06",
    "count" : 53
},
{
    "term" : "nike1",
    "year" : "2015",
    "month" : "06",
    "day" : "06",
    "count" : 121
},
{
    "term" : "nike1",
    "year" : "2014",
    "month" : "03",
    "day" : "07",
    "count" : 110
}
]

最后的结果不是预期的

{
    "term" : "nike1",
    "year" : "2014",
    "month" : "03",
    "day" : "07",
    "count" : 110
 }

因为年月日没有完全满足我通过的条件。我知道我遗漏了 something.Can 谁能指出来？

Answer 1

这样试试：

db.products.aggregate([
{
   $match: {
      year: "2015",
      month: "06",
      day: "06"
   }
},
{
   $group: {
     _id: {
        year: "$year",
        month: "$month",
        day: "$day",
        term: "$term"
     }
     count: {
        $sum: "$count"
     }
   }
}
])

Answer 2

使用聚合解决了这个问题

db.products.aggregate([
       {$match:
          {$and:[
                 {year:"2015"},
                 {month:"06"},
                 {day:"06"}]}},
          {$group:{
                   _id : "$year",
                   _id : "$month",
                   _id : "$day",
                   _id :"$term",
           totalcount : {
                         $sum : "$count"
                        }
       }
     }
    ])

Answer 3

根据 this，db.collection.group() 命令接受字段 cond 作为选择标准，而不是 $match。试试吧。

Answer 4

如果您只想按年月日分组，那么：

db.products.aggregate([{
    $group: {
        _id: { year:"$year", month:"$month", day:"$day"},
        sumOfCount: { $sum:"$count" }
    }   
}])

如果你也想过滤那么：

db.products.aggregate([{
    $match: {
        year: "2015",
        month: "06",
        day: "06"
    }
}, {    
    $group: {
        _id: { year:"$year", month:"$month", day:"$day"},
        sumOfCount: { $sum:"$count" }
    }   
}])

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