REVISING question. Will be updated soon.
Demo - https://mongoplayground.net/p/ksay82IaGHs
Group by TeacherID
and TeacherID
and get occurrence of the combination, $sort by occurrence
in descending order.
db.collection.aggregate([
{ $group: { _id: { TeacherID: "$TeacherID", StudentID: "$StudentID" }, occurrence: { $sum: 1 } } },
{ $sort: { "occurrence": -1 } }
]);
[ { "_id": { "StudentID": 2, "TeacherID": 212 }, "occurrence": 3 }, { "_id": { "StudentID": 4, "TeacherID": 223 }, "occurrence": 1 }, ..... ]
If you want the top record
Demo - https://mongoplayground.net/p/zBsGdAOdYwy
{ "$limit": 1 }
Demo - https://mongoplayground.net/p/G2KIVcjtYII
If you want to check for specific TeacherID use $match
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