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MongoDB query to update each field of documents in collection with a formula?
To update each field of documents in collection with a formula, use MongoDB update(). Let us create a collection with documents −
> db.demo749.insertOne({"details":[{"id":1,a:10},{"id":2,a:5},{"id":3,a:20}]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5eae6fb0a930c785c834e565")
}Display all documents from a collection with the help of find() method −
> db.demo749.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5eae6fb0a930c785c834e565"),
"details" : [
{
"id" : 1,
"a" : 10
},
{
"id" : 2,
"a" : 5
},
{
"id" : 3,
"a" : 20
}
]
}Following is the query to update each field of documents in collection with a formula −
> db.demo749.update(
... {
...
... },
... {
... $mul: { "details.$[].a": 2/5}
... },
... { multi:true}
... )
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Display all documents from a collection with the help of find() method −
> db.demo749.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5eae6fb0a930c785c834e565"),
"details" : [
{
"id" : 1,
"a" : 4
},
{
"id" : 2,
"a" : 2
},
{
"id" : 3,
"a" : 8
}
]
}
Updated on: 30-Jun-2020
154 Views
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