//比較符號
$gt -------- greater than >
$gte --------- gt equal >=
$lt -------- less than <
$lte --------- lt equal <=
$ne ----------- not equal !=
$eq -------- equal =
常規查詢:
db.form.find({$expr:{$gt:["$approve_create", "$approve_delete"]}})
聚合查詢:
db.form.aggregate({$match:{$expr:{$gt:["$approve_create", "$approve_delete"]}}})