MongoDB Advanced Query

The logical structure of MongoDB is a hierarchical structure. Mainly consists of three parts: Document, Collection (collection), database. A logical structure is a logical structure used by user-facing users to develop applications using MONGODB.

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

Multiple Documents form a collection collection a table equivalent to a relational database.

Multiple collections collection logically together are database databases.

A MongoDB instance supports multiple databases.

MongoDB Conditional Query

Db.collection.find ({"field": {$gt: Value}})//greater Than

Db.collection.find ({"field": {$lt: Value}}); Less than: Field < value

Db.collection.find ({"field": {$gte: Value}}); Greater than or equal to: field >= value

Db.collection.find ({"field": {$lte: Value}}); Less than equals: field <= value

You can do this if you want to satisfy multiple conditions at the same time

Db.collection.find ({"field": {$gt: value1, $lt: value2}}); value1 < Field < value

$all match all the values that must be met in [] for example:

Db.users.find ({age: {$all: [6, 8]}});

Can query {name: ' David ', age:26, Age: [6, 8, 9]}

But the query does not show {name: ' David ', age:26, Age: [6, 7, 9]}

$exists determine if a field exists

Querying all records that exist in the age field

Db.users.find ({age: {$exists: true}});

Query all records that do not exist in the name field

Db.users.find ({name: {$exists: false}});

$ne Not equal to

The value of the query x is not equal to 3 of the data

Db.things.find ({x: {$ne: 3}});

$in contains

Querying the value of x within the 2,4,6 range of data

Db.things.find ({x:{$in: [2,4,6]}});

$nin does not contain

Querying the value of x outside the 2,4,6 range of data

Db.things.find ({x:{$nin: [2,4,6]}});

$size number of array elements

For {name: ' David ', age:26, Favorite_number: [6, 7, 9]} record

Match Db.users.find ({favorite_number: {$size: 3}});

Mismatch Db.users.find ({favorite_number: {$size: 2}});

Regular expression Matching

Query mismatch name=b* lead record

Db.users.find ({name: {$not:/^b.*/}});

Skip limit Returns the start of a record

Returns 5 records starting from 3rd record (limit 3, 5)

Db.users.find (). Skip (3). Limit (5);

Sort sorts

With age ascending ASC

Db.users.find (). Sort ({age:1});

Descending desc by age

Db.users.find (). Sort ({Age:-1});

MongoDB Advanced Query