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How to select a single field in MongoDB?
You can select a single field in MongoDB using the following syntax:
db.yourCollectionName.find({"yourFieldName":yourValue},{"yourSingleFieldName":1,_id:0});In the above syntax "yourSingleFieldName":1, _id:0 means get all data from one field without _id.
To understand the above syntax, let us create a collection with document. The query to create a collection with document is as follows:
> db.singleFieldDemo.insertOne({"StudentName":"David","StudentAge":28}); { "acknowledged" : true, "insertedId" : ObjectId("5c6eba356fd07954a489067c") } > db.singleFieldDemo.insertOne({"StudentName":"Bob","StudentAge":18}); { "acknowledged" : true, "insertedId" : ObjectId("5c6eba406fd07954a489067d") } > db.singleFieldDemo.insertOne({"StudentName":"Chris","StudentAge":24}); { "acknowledged" : true, "insertedId" : ObjectId("5c6eba4c6fd07954a489067e") } > db.singleFieldDemo.insertOne({"StudentName":"Robert","StudentAge":26}); { "acknowledged" : true, "insertedId" : ObjectId("5c6eba586fd07954a489067f") }
Now you can display all documents from a collection with the help of find() method. The query is as follows:
> db.singleFieldDemo.find().pretty();
The following is the output:
{
"_id" : ObjectId("5c6eba356fd07954a489067c"),
"StudentName" : "David",
"StudentAge" : 28
}
{
"_id" : ObjectId("5c6eba406fd07954a489067d"),
"StudentName" : "Bob",
"StudentAge" : 18
}
{
"_id" : ObjectId("5c6eba4c6fd07954a489067e"),
"StudentName" : "Chris",
"StudentAge" : 24
}
{
"_id" : ObjectId("5c6eba586fd07954a489067f"),
"StudentName" : "Robert",
"StudentAge" : 26
}Here is the query to select a single field:
> db.singleFieldDemo.find({"StudentAge":18},{"StudentName":1,"_id":0});The following is the output:
{ "StudentName" : "Bob" }
Updated on: 14-Sep-2023
24K+ Views
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