Pymongo 聚合管道

Question

修訂問題。 將很快更新。

Answer 1

演示 - https://mongoplayground.net/p/ksay82IaGHs

按TeacherID和TeacherID ，得到組合的出現次數，$sort 按occurrence降序排列。

db.collection.aggregate([
  { $group: { _id: { TeacherID: "$TeacherID", StudentID: "$StudentID" }, occurrence: { $sum: 1 } } },
  { $sort: { "occurrence": -1 } }
]);

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Output

 [ { "_id": { "StudentID": 2, "TeacherID": 212 }, "occurrence": 3 }, { "_id": { "StudentID": 4, "TeacherID": 223 }, "occurrence": 1 }, ..... ]

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如果你想要最高紀錄

演示 - https://mongoplayground.net/p/zBsGdAOdYwy

 { "$limit": 1 }

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演示 - https://mongoplayground.net/p/G2KIVcjtYII

如果要檢查特定的 TeacherID，請使用 $match