mongodb dot notation array

MongoDB is a document database, and each document (DOC) represents a record of the data. Instead of the relational DB row can only use simple data types, doc can use complex data types: inline doc, arrays. An array of MongoDB is a collection of

1. PrefaceIn the previous article, we introduced MongoDB. Now, let's look at how to do a regular crud operation in MongoDB. After all, as a storage system, it is the basic function of the data to be increased and censored operation.The additions and

_ Id Index An index is automatically created for the _ id field for all sets except the set of capacity. This is a special index and cannot be deleted. The _ id index forces that its keywords are unique (except for some scenarios in the partition

1. PrefaceIn this blog post, we will learn how to query the data in MongoDB. When we store the data in MongoDB, we need to query the data. After all, the query operation in the crud operation is our most frequently used operation in our system. We

MongoDB uses the Bson format to store data records. Such as:Document structureThe document consists of a key-value pair with the following structure: {Field1:value1,Field2:value2,...Fieldn:valuen}? The value of the field can be any

Regular expressions are often used to search for any pattern or text in a string in all languages. MongoDB also provides a string pattern of regular expression functionality using regular Expression $regex operator. MongoDB uses Pcre

In MongoDB, the Db.collection.find () method is used to retrieve documents from the collection. The Db.collection.find () method returns a cursor that retrieves the document. The Db.collection.findOne () method also performs a read operation,

By default, queries in MongoDB return all fields in matching documents. To limit the amount of data from MongoDB sends to applications, you can include a projection document in the Quer Y operation.Projection DocumentThe projection document limits

Basic concepts: 1. Document --> corresponds to the row of the relational database, that is, a record. It is more powerful than the row functions of relational databases, and more like a specific object. The document is displayed in the form of a Map.

Connecting to a database Mongoclient VS Connection Class Mongoclient (Pymongo.common.BaseObject) | Connection to MongoDB. | | Method Resolution Order: | mongoclient | Pymongo.common.BaseObject | __builtin__.object |class Connection