MongoDB (class 26 Aggregation (number of collections taken))

Source: Internet
Author: User

3.7 Aggregation (emphasis)

The statistical operation of information is aggregation (straightforward: grouping statistics is an aggregation operation).

3.7.1 The amount of data taken by the collection

For the amount of data in a collection, it is possible to use the count () function directly in MongoDB.

Example: counting the amount of data in a students table

Db.students.count ()

Example: fuzzy query

Db.students.count ({"name":/Zhang/I})

In the information query, do not set the conditions than

MongoDB (class 26 Aggregation (number of collections taken))

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