Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
How to return only unique values (no duplicates) in MongoDB?
You can use distinct() to return only unique values. The syntax is as follows −
db.yourCollectionName.distinct("yourFieldName");To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −
> db.returnOnlyUniqueValuesDemo.insertOne({"CusomerName":"Larry","CustomerAge":23});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ed7262f684a30fbdfd580")
}
> db.returnOnlyUniqueValuesDemo.insertOne({"CusomerName":"Mike","CustomerAge":21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ed72d2f684a30fbdfd581")
}
> db.returnOnlyUniqueValuesDemo.insertOne({"CusomerName":"Sam","CustomerAge":21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ed7322f684a30fbdfd582")
}
> db.returnOnlyUniqueValuesDemo.insertOne({"CusomerName":"Carol","CustomerAge":25});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ed73a2f684a30fbdfd583")
}
> db.returnOnlyUniqueValuesDemo.insertOne({"CusomerName":"David","CustomerAge":22});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ed74a2f684a30fbdfd584")
}
> db.returnOnlyUniqueValuesDemo.insertOne({"CusomerName":"Chris","CustomerAge":23});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8ed7582f684a30fbdfd585")
}Display all documents from a collection with the help of find() method. The query is as follows −
> db.returnOnlyUniqueValuesDemo.find().pretty();
The following is the output −
{
"_id" : ObjectId("5c8ed7262f684a30fbdfd580"),
"CusomerName" : "Larry",
"CustomerAge" : 23
}
{
"_id" : ObjectId("5c8ed72d2f684a30fbdfd581"),
"CusomerName" : "Mike",
"CustomerAge" : 21
}
{
"_id" : ObjectId("5c8ed7322f684a30fbdfd582"),
"CusomerName" : "Sam",
"CustomerAge" : 21
}
{
"_id" : ObjectId("5c8ed73a2f684a30fbdfd583"),
"CusomerName" : "Carol",
"CustomerAge" : 25
}
{
"_id" : ObjectId("5c8ed74a2f684a30fbdfd584"),
"CusomerName" : "David",
"CustomerAge" : 22
}
{
"_id" : ObjectId("5c8ed7582f684a30fbdfd585"),
"CusomerName" : "Chris",
"CustomerAge" : 23
}Here is the query to return only unique values −
> db.returnOnlyUniqueValuesDemo.distinct("CustomerAge");The following is the output:
[ 23, 21, 25, 22 ]
Updated on: 30-Jul-2019
862 Views
Advertisements