db.avoidDuplicateEntriesDemo.createIndex({"UserName":1},{unique:true});{ &a"> Avoid duplicate entries in MongoDB?-MongoDB-php.cn
Home> Database> MongoDB> body text

Avoid duplicate entries in MongoDB?

WBOY
Release: 2023-08-29 08:29:13
forward
1419 people have browsed it

避免 MongoDB 中出现重复条目​​?

To avoid duplicate entries in MongoDB, you can use createIndex(). The syntax is as follows -

db.yourCollectionName.createIndex({"yourFieldName":1},{unique:true});
Copy after login

Let us implement the above syntax. The query to avoid duplicate entries in MongoDB is as follows -

> db.avoidDuplicateEntriesDemo.createIndex({"UserName":1},{unique:true}); { "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 }
Copy after login

Now insert some records in the above collection. The query to insert a record is as follows -

> db.avoidDuplicateEntriesDemo.insertOne({"UserName":"John"}); { "acknowledged" : true, "insertedId" : ObjectId("5c90e1824afe5c1d2279d697") }
Copy after login

Whenever you try to insert the same record again, you will get an error -

> db.avoidDuplicateEntriesDemo.insertOne({"UserName":"John"}); 2019-03-19T18:03:08.465+0530 E QUERY [js] WriteError: E11000 duplicate key error collection: test.avoidDuplicateEntriesDemo index: UserName_1 dup key: { : "John" } : WriteError({ "index" : 0, "code" : 11000, "errmsg" : "E11000 duplicate key error collection: test.avoidDuplicateEntriesDemo index: UserName_1 dup key: { : \"John\" }", "op" : { "_id" : ObjectId("5c90e1844afe5c1d2279d698"), "UserName" : "John" } }) WriteError@src/mongo/shell/bulk_api.js:461:48 Bulk/mergeBatchResults@src/mongo/shell/bulk_api.js:841:49 Bulk/executeBatch@src/mongo/shell/bulk_api.js:906:13 Bulk/this.execute@src/mongo/shell/bulk_api.js:1150:21 DBCollection.prototype.insertOne@src/mongo/shell/crud_api.js:252:9 @(shell):1:1
Copy after login

Let’s insert another record. The query is as follows -

> db.avoidDuplicateEntriesDemo.insertOne({"UserName":"Carol"}); { "acknowledged" : true, "insertedId" : ObjectId("5c90e18d4afe5c1d2279d699") }
Copy after login

Display all the documents in the collection with the help of find() method. The query is as follows -

> db.avoidDuplicateEntriesDemo.find();
Copy after login

The following is the output -

{ "_id" : ObjectId("5c90e1824afe5c1d2279d697"), "UserName" : "John" } { "_id" : ObjectId("5c90e18d4afe5c1d2279d699"), "UserName" : "Carol" }
Copy after login

The above is the detailed content of Avoid duplicate entries in MongoDB?. For more information, please follow other related articles on the PHP Chinese website!

source:tutorialspoint.com
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
About us Disclaimer Sitemap
php.cn:Public welfare online PHP training,Help PHP learners grow quickly!