mongodb中find $ne null 與$exists的區別

1. test collection 數據爲：web db.test.find() { "_id" : ObjectId("5be29949f1acad52e4c10b98"), "name" : "jane", "info" : [ ] } { "_id" : ObjectId("5be29952f1acad52e4c10b99"), "name" : "mike", "info" : { }

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