{
userId: OjbectId,
updatedAt: Date
}
I am a rookie, ask for advice.
If you know how to write in SQL, the same principle applies to MongoDB. This is a very common grouping aggregation query. The answer is below, but I still hope you can try to search for the answer online and exercise your ability to solve problems independently.
db.collection.aggregate([ {$group: {_id: "$userId", maxUpdatedAt: {$max: "$updatedAt"}}} ]);
UseaggregationThe$maxOperator can easily get the answer.