Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{"key":1,value:30},{"key":2,value:4}]
Query
db.collection.update({key:1},[{$set:{"value":{$cond:[{$gt:[{$subtract:["$value",44]},0]},{$subtract:["$value",44]},0]}}}])
Result