How do i find a particular record in mongodb?
Docs Home → MongoDB Manual Show db.collection.find(query, projection, options)
Importantmongosh MethodThis page documents a For MongoDB API drivers, refer to the language-specific MongoDB driver documentation. For the legacy
Selects documents in a collection or view and returns a cursor to the selected documents.
ImportantLanguage ConsistencyThe
For fields in an embedded documents, you can specify the field using either:
The A
See Projection Examples. Executing To access the returned documents with a driver, use the appropriate cursor handling mechanism for the driver language. TipTo specify the read concern for MongoDB treats some data types as equivalent for comparison purposes. For instance, numeric types undergo conversion before comparison. For most data types, however, comparison operators only perform comparisons on documents where the BSON type of the target field matches the type of the query operand. Consider the following collection:
The following query uses
The query returns the following documents:
The document with The document with NoteNew in version 4.0. For cursors created inside a session, you cannot call Similarly, for cursors created outside of a session, you cannot call
Starting in MongoDB 3.6, MongoDB drivers and If a session is idle for longer than 30 minutes, the MongoDB server marks that session as expired and may close it at
any time. When the MongoDB server closes the session, it also kills any in-progress operations and open cursors associated with the session. This includes cursors configured with For operations that may be idle for longer than 30 minutes, associate the operation with an explicit session using
ImportantIn most cases, multi-document transaction incurs a greater performance cost over single document writes, and the availability of multi-document transactions should not be a replacement for effective schema design. For many scenarios, the denormalized data model (embedded documents and arrays) will continue to be optimal for your data and use cases. That is, for many scenarios, modeling your data appropriately will minimize the need for multi-document transactions. For additional transactions usage considerations (such as runtime limit and oplog size limit), see also Production Considerations. Starting in MongoDB 4.2, if the client that issued
The examples in this section use documents from the bios collection where the documents generally have the form:
To create and populate the The
To find documents that match a set of selection criteria, call MongoDB provides various query operators to specify the criteria.
For a list of the query operators, see Query Selectors. Combine comparison operators to specify ranges for a field. The following
operation returns from the bios collection documents where
For a list of the query operators, see Query Selectors. The following operation returns all the documents from the bios collection where
For a list of the query operators, see Query Selectors. The following examples query the The following operation returns documents in the bios collection where the embedded document
The
The following operation returns documents in the bios collection where the embedded document
The query matches the document where the
For more information and examples, see also Query on Embedded/Nested Documents. The following examples query the
For more information and examples of querying an array, see:
For a list of array specific query operators, see Array. The following examples query the
For more information and examples of querying an array, see:
For a list of array specific query operators, see Array. The
projection parameter specifies which fields to return. The parameter contains either include or exclude specifications, not both, unless the exclude is for the NoteUnless the The following operation finds all documents in the bios collection and returns only the
NoteUnless the The following
operation queries the bios collection and returns all fields except the
NoteUnless the The following
operation finds documents in the bios collection and returns only the
The following operation queries the bios collection and returns the
Starting in MongoDB 4.4, you can also specify embedded fields using the nested form, e.g.
Starting in MongoDB 4.4, With the use of aggregation expressions and syntax, you can project new fields or project existing fields with new values. For example, the following operation uses aggregation expressions to override the value of the
To set the
TipSee also:The In To manually iterate over the results, assign the returned cursor to a variable with the The following example uses the variable
The following example uses the cursor method
To print, you can also use the
The following example uses the cursor method
The
The
The Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks. The
The following statements chain cursor methods
The two statements are equivalent; i.e. the order in which you chain the
You can specify query options to modify query behavior and indicate how results are returned. For example, to define variables that you can access elsewhere in the Create a
collection
The following example defines a
Output:
To see all available query options, see FindOptions. How do I find a specific data in MongoDB?Find() Method. In MongoDB, find() method is used to select documents in a collection and return a cursor to the selected documents. Cursor means a pointer that points to a document, when we use find() method it returns a pointer on the selected documents and returns one by one.
How do I view a specific collection in MongoDB?To obtain a list of MongoDB collections, we need to use the Mongo shell command show collections . This command will return all collections created within a MongoDB database. To be able to use the command, we'll first need to select a database where at least one collection is stored.
How do I fetch a specific column in MongoDB?“how to select specific columns in mongodb” Code Answer's. db. student. find({}, 'roll _id'); // <--- Just multiple fields name space separated.. db. student. find({}). select('roll _id'); // <--- Just multiple fields name space separated.. db. student. find({}, {'roll' : 1 , '_id' : 1 ); // <---- Old lengthy boring way.. How do I query unique records in MongoDB?To get unique values and ignore duplicates, use distinct() in MongoDB. The distinct() finds the distinct values for a specified field across a single collection and returns the results in an array.
|