The index stores the value of a specific field or set of fields, ordered by the value of the field. The ordering of the index entries supports efficient equality matches and range-based query operations. In add
Node.js You can also specify embedded fields using the nested form. For example, { item: 1, status: 1, size: { uom: 1 } }. Suppress Specific Fields in Embedded Documents You can suppress specific fields in an embedded document. Use the dot notation to refer to the embedded field in...
The index stores the value of a specific field or set of fields, ordered by the value of the field. The ordering of the index entries supports efficient equality matches and range-based query operations. In addition, MongoDB can return sorted results using the ordering in the index. ...
Equality Match on Fields db.users.find( {"favorites.artist":"Picasso"} ) Query on Arrays When the field holds an array, you can query for an exact array match or for specific values in the array If you specify multiple conditions without using the $elemMatch operator, then some combination...
A MongoDB Query Filter. The findOne action returns the first document in the collection that matches this filter. projection projection object A MongoDB Query Projection. Depending on the projection the returned document will either omit specific fields or include only specified fields or values ...
If your application’s query patterns are known in advance, then you should use more selective indexes on the specific fields accessed by the queries. Use text search to match words inside a field Regular indexes are useful for matching the entire value of a field. If you only want to ...
Return All But the Excluded Fields db.inventory.find( { status: "A" }, { status: 0, instock: 0 } ) With the exception of the _id field, you cannot combine inclusion and exclusion statements in projection documents. Return Specific Fields in Embedded Documents ...
into a JSON string. For example, doc1, doc2, and doc3 are three MongoDB documents that contain different fields. The fields are represented by keys instead of key-value pairs. The keys a and b are common fields in these three documents. The key x_n represents a document-specific field...
@AutowiredprivateMongoTemplatemongoTemplate;publicList<Document>querySpecificColumns(StringcollectionName,StringcolumnName){Queryquery=newQuery();query.fields().include(columnName);// 指定需要查询的列名returnmongoTemplate.find(query,Document.class,collectionName);} ...
Set the project property: Specifies the fields to return in the documents that match the query filter. To return all fields in the matching documents, omit this parameter. Type: string (or Expression with resultType string). Parameters: project - the project value to set. Returns:...