Comparing two different fields in mongoDB-CodePudding

How to compare two properties in MongoDB, I want to find and delete all those rows where "income per annum" is greater than "savings per annum"??

CodePudding user response：

You can use deleteMany. Documents that pass the filter will be deleted. For example

*$expr is needed because we need to compare 2 fields. The query $gt operator takes a field and a value, so here the aggregate $gt is used with $expr

db.collection.deleteMany(
  {"$expr": {"$gt": ["$income-per-annum", "$savings-per-annum"]}});

CodePudding user response：

Maybe something like this:

db.collection.find({
 "$expr": {
  "$gt": [
    "$income",
    "$savings"
   ]
 }
 }).forEach(function(doc){ db.collection.remove(_id:doc._id)})

Explained:

Find all affected documents via $expr and loop over them via forEach to remove one by one.