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Insert in MongoDB without duplicates
To insert records in MongoDB and avoid duplicates, use “unique:true”. Let us first create a collection with documents.
Here, we are trying to add duplicate records −
> db.insertWithoutDuplicateDemo.createIndex({"StudentFirstName":1},{ unique: true } );
{
"createdCollectionAutomatically" : true,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}
> db.insertWithoutDuplicateDemo.insert({"StudentFirstName":"Chris"},{ upsert: true });
WriteResult({ "nInserted" : 1 })
> db.insertWithoutDuplicateDemo.insert({"StudentFirstName":"David"},{ upsert: true });
WriteResult({ "nInserted" : 1 })
> db.insertWithoutDuplicateDemo.insert({"StudentFirstName":"Chris"},{ upsert: true });
WriteResult({
"nInserted" : 0,
"writeError" : {
"code" : 11000,
"errmsg" : "E11000 duplicate key error collection: test.insertWithoutDuplicateDemo index: StudentFirstName_1 dup key: { : \"Chris\" }"
}
})
> db.insertWithoutDuplicateDemo.insert({"StudentFirstName":"Bob"},{ upsert: true });
WriteResult({ "nInserted" : 1 })Following is the query to display all documents from a collection with the help of find() method −
> db.insertWithoutDuplicateDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5e064405150ee0e76c06a054"),
"StudentFirstName" : "Chris"
}
{
"_id" : ObjectId("5e064410150ee0e76c06a055"),
"StudentFirstName" : "David"
}
{ "_id" : ObjectId("5e06441f150ee0e76c06a057"), "StudentFirstName" : "Bob" }
Updated on: 27-Mar-2020
7K+ Views
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