MongoDB的數據與彙總

分組我有收集數據是這樣的：MongoDB的數據與彙總

> db.LogBuff.find() 
{ "_id" : ObjectId("578899d5d2b76f77d083f16c"), "SUBJECT" : "DD", "SYS" : "A" } 
{ "_id" : ObjectId("578899d5d2b76f77d083f16d"), "SUBJECT" : "AA", "SYS" : "B" } 
{ "_id" : ObjectId("578899d5d2b76f77d083f16e"), "SUBJECT" : "BB", "SYS" : "A" } 
{ "_id" : ObjectId("578899d5d2b76f77d083f16f"), "SUBJECT" : "AA", "SYS" : "C" } 
{ "_id" : ObjectId("578899d5d2b76f77d083f170"), "SUBJECT" : "BB", "SYS" : "A" } 
{ "_id" : ObjectId("578899d5d2b76f77d083f171"), "SUBJECT" : "BB", "SYS" : "A" } 
{ "_id" : ObjectId("578899d5d2b76f77d083f172"), "SUBJECT" : "CC", "SYS" : "B" }

而且我想，如下提取輸出（帶有明顯的「SYS」值）

{"SUBJECT" : "AA", "SYS" : ["A","B","C","D"]} 
{"SUBJECT" : "BB", "SYS" : ["A","B","C","D"]} 
{"SUBJECT" : "CC", "SYS" : ["A","B","C"]}

這裏是我的代碼和我被困在中間，請幫我在_id這個

db.LogBuff.aggregate([{ 
    "$unwind": "$SYS" 
}, { 
    "$group": { 
      _id: { 
        "_id": "$SUBJECT" 
      }, 
      SYST: { 
        $addToSet: "$SYS" 
      } 
    } 
}, { 
    "$unwind": "$SYST" 
}, { 
    "$group": { 
      _id: { 
      "SUBJECT": "$_id", 
        "SYST":"$SYST" 
      } 
    } 
}])

來源

2016-07-22 Kavinda

是什麼在第一管道使用了'$ unwind'操作的時候'SYS'領域是不是一個數組？爲什麼不直接運行'db.LogBuff.aggregate（[ {$ group「：{ 」_id「：」$ SUBJECT「，」sys「：{」$ addToSet「：」$ SYS「}} } } ]）？ – chridam

剛組排序，addToSet個的SYS值：

db.LogBuff.aggregate([ 
    { 
    "$group": { 
      _id: { 
        "_id": "$SUBJECT" 
      }, 
      SYST: { 
        $addToSet: "$SYS" 
      } 
     } 
    } 
])

無需開卷，一個group應該得到你想要的結果。

您例如數據組聚集結果：

{ "_id" : { "_id" : "CC" }, "SYST" : [ "B" ] } 
{ "_id" : { "_id" : "BB" }, "SYST" : [ "A" ] } 
{ "_id" : { "_id" : "AA" }, "SYST" : [ "C", "B" ] } 
{ "_id" : { "_id" : "DD" }, "SYST" : [ "A" ] }

來源

2016-07-22 07:59:04 sergiuz

非常感謝 – Kavinda

MongoDB的數據與彙總

回答

相關問題