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按多個(gè)字段劃分的MongoDB組值

MongoDB

胡子哥哥 2019-06-26 13:27:41

按多個(gè)字段劃分的MongoDB組值例如，我有以下文件：{ "addr": "address1", "book": "book1"},{ "addr": "address2", "book": "book1"},{ "addr": "address1", "book": "book5"},{ "addr": "address3", "book": "book9"},{ "addr": "address2", "book": "book5"},{ "addr": "address2", "book": "book1"},{ "addr": "address1", "book": "book1"},{ "addr": "address15", "book": "book1"},{ "addr": "address9", "book": "book99"},{ "addr": "address90", "book": "book33"},{ "addr": "address4", "book": "book3"},{ "addr": "address5", "book": "book1"},{ "addr": "address77", "book": "book11"},{ "addr": "address1", "book": "book1"}諸若此類。我怎樣才能提出一個(gè)請(qǐng)求，它將描述每個(gè)地址的前N位地址和最上面的M類書籍？預(yù)期結(jié)果實(shí)例：地址1\book_1：5書2：10書3：50共計(jì)：65______________________地址2\book_1：10書2：10|...手冊(cè)M：10共計(jì)：m*10...______________________地址N_1：20書2：20|...手冊(cè)M：20共計(jì)：m*20

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3 回答

鳳凰求蠱

TA貢獻(xiàn)1825條經(jīng)驗(yàn) 獲得超4個(gè)贊

下面的查詢將提供與所需響應(yīng)中提供的結(jié)果完全相同的結(jié)果：

db.books.aggregate([
    {
        $group: {
            _id: { addresses: "$addr", books: "$book" },
            num: { $sum :1 }
        }
    },
    {
        $group: {
            _id: "$_id.addresses",
            bookCounts: { $push: { bookName: "$_id.books",count: "$num" } }
        }
    },
    {
        $project: {
            _id: 1,
            bookCounts:1,
            "totalBookAtAddress": {
                "$sum": "$bookCounts.count"
            }
        }
    }])

答復(fù)如下：

/* 1 */{
    "_id" : "address4",
    "bookCounts" : [
        {
            "bookName" : "book3",
            "count" : 1
        }
    ],
    "totalBookAtAddress" : 1},/* 2 */{
    "_id" : "address90",
    "bookCounts" : [
        {
            "bookName" : "book33",
            "count" : 1
        }
    ],
    "totalBookAtAddress" : 1},/* 3 */{
    "_id" : "address15",
    "bookCounts" : [
        {
            "bookName" : "book1",
            "count" : 1
        }
    ],
    "totalBookAtAddress" : 1},/* 4 */{
    "_id" : "address3",
    "bookCounts" : [
        {
            "bookName" : "book9",
            "count" : 1
        }
    ],
    "totalBookAtAddress" : 1},/* 5 */{
    "_id" : "address5",
    "bookCounts" : [
        {
            "bookName" : "book1",
            "count" : 1
        }
    ],
    "totalBookAtAddress" : 1},/* 6 */{
    "_id" : "address1",
    "bookCounts" : [
        {
            "bookName" : "book1",
            "count" : 3
        },
        {
            "bookName" : "book5",
            "count" : 1
        }
    ],
    "totalBookAtAddress" : 4},/* 7 */{
    "_id" : "address2",
    "bookCounts" : [
        {
            "bookName" : "book1",
            "count" : 2
        },
        {
            "bookName" : "book5",
            "count" : 1
        }
    ],
    "totalBookAtAddress" : 3},/* 8 */{
    "_id" : "address77",
    "bookCounts" : [
        {
            "bookName" : "book11",
            "count" : 1
        }
    ],
    "totalBookAtAddress" : 1},/* 9 */{
    "_id" : "address9",
    "bookCounts" : [
        {
            "bookName" : "book99",
            "count" : 1
        }
    ],
    "totalBookAtAddress" : 1}

反對(duì) 回復(fù) 2019-06-26