Queries
Queries
The MongoDB Query Language comes with a powerful combination of query commands.
Count Queries
The following two commands both retrieve the count of the filtered documents:
db.collection.count( <filter>, <options> )
db.collection.countDocuments( <filter>, <options> )
If the result does not need to be accurate and can be estimated, the following command can be used:
db.collection.estimatedDocumentCount( <options> )
Simple Queries
When simple queries need to be executed, the following command can be used:
db.collection.find( <filter>, <projection> )
To number of retrieved records can also directly be limited to one:
db.collection.findOne( <filter>, <projection> )
Complex Queries
Complex queries can be constructed using the aggregation pipeline
db.collection.aggregate( <pipeline>, <options> )