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Create a Unique Index. To create a unique index, use the db.collection.createIndex() method with the unique option set to true. db. collection. createIndex ( <key and index type specification>, { unique: true } ) Unique Index on a Single Field.
- Unique Indexes — MongoDB Manual
To create a unique index, use the...
- Create a Unique Index — MongoDB Manual
To create a unique index, consider the following prototype:...
- Unique Indexes — MongoDB Manual
To create a unique index, use the db.collection.createIndex() method with the unique option set to true. db. collection. createIndex ( <key and index type specification>, { unique: true } ) Unique Index on a Single Field. For example, to create a unique index on the user_id field of the members collection, use the following operation in mongosh:
8 lip 2024 · In MongoDB, unique indexes can be created at the collection level using the createIndex () method or by specifying the unique option when defining the index in a collection’s schema. Example 1: Unique Index on a Single Field. // Create a unique index on the "username" field of the "users" collection.
To create a unique index, consider the following prototype: copy. db.collection.ensureIndex({a:1},{unique:true}) For example, you may want to create a unique index on the "tax-id": of the accounts collection to prevent storing multiple account records for the same legal entity: copy. db.accounts.ensureIndex({"tax-id":1},{unique:true})
2 lut 2024 · In MongoDB, a unique constraint can be applied to a field using an index. Creating a unique index on a field will prevent the insertion or updating of a document if it results in a duplicate value for that index. The unique index guarantees that the indexed fields do not store duplicate values.
16 lis 2021 · You can create an index before the collection is created. For example, I don't have a collection called as users, and I am creating an unique index on the email field. From the mongo shell or mongosh: db.users.createIndex( { email: 1 }, { unique: true } )
A unique index enforces the uniqueness of values for a field in a collection. A unique compound index enforces the uniqueness of combination of values of multiple fields in a collection. Use the createIndex() method with the option { unique: true } to create a unique index and compound unique index.
