Shulou(Shulou.com)06/01 Report--

The logical structure of MongoDB is a hierarchical structure. It is mainly composed of document (document), collection (collection) and database (database). Logical structure is user-oriented what users use to develop applications using MongoDB is the logical structure.

The document document of MongoDB is equivalent to a row of records in a relational database.

Multiple documents form a collection collection is equivalent to tables in a relational database.

Multiple collections collection are logically organized together as database database.

A single MongoDB instance supports multiple database database.

Mongodb conditional query

Db.collection.find ({"field": {$gt:value}}) / / is greater than

Db.collection.find ({"field": {$lt: value}}); / / less than: field

= value

Db.collection.find ({"field": {$lte: value}}); / less than or equal to: field

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