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Perform conditional upserts or updates in MongoDB
For conditional upserts or updates, you can use $max operator. Let us first create a collection with documents
>db.conditionalUpdatesDemo.insertOne({"_id":100,"StudentFirstScore":89,"StudentSecondScore":78,"BiggestScore":89});
{ "acknowledged" : true, "insertedId" : 100 }
>db.conditionalUpdatesDemo.insertOne({"_id":101,"StudentFirstScore":305,"StudentSecondScore":560,"BiggestScore":1050});
{ "acknowledged" : true, "insertedId" : 101 }
>db.conditionalUpdatesDemo.insertOne({"_id":103,"StudentFirstScore":560,"StudentSecondScore":789,"BiggestScore":880});
{ "acknowledged" : true, "insertedId" : 103 }
Following is the query to display all documents from a collection with the help of find() method:
> db.conditionalUpdatesDemo.find().pretty();This will produce the following output
{
"_id" : 100,
"StudentFirstScore" : 89,
"StudentSecondScore" : 78,
"BiggestScore" : 89
}
{
"_id" : 101,
"StudentFirstScore" : 305,
"StudentSecondScore" : 560,
"BiggestScore" : 1050
}
{
"_id" : 103,
"StudentFirstScore" : 560,
"StudentSecondScore" : 789,
"BiggestScore" : 880
}Following is the query for conditional upserts or updates in MongoDB
> db.conditionalUpdatesDemo.update( { _id: 100 }, { $max: { "BiggestScore": 150 } } );
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Let us check the field “BiggestScore” is updated with value 150 or not for _id 100
> db.conditionalUpdatesDemo.find().pretty();
This will produce the following output
{
"_id" : 100,
"StudentFirstScore" : 89,
"StudentSecondScore" : 78,
"BiggestScore" : 150
}
{
"_id" : 101,
"StudentFirstScore" : 305,
"StudentSecondScore" : 560,
"BiggestScore" : 1050
}
{
"_id" : 103,
"StudentFirstScore" : 560,
"StudentSecondScore" : 789,
"BiggestScore" : 880
}
Updated on: 30-Jul-2019
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