Novice MongoDB Learning---(iv) MONGODB conditional operator

The conditional operator is used to compare two expressions and fetch data from a MongoDB collection.

The condition operators in MongoDB are:

• (>) Greater than-$GT
• (<) less than-$lt
• (>=) greater than or equal to-$gte
• (<=) less than or equal to-$lte

> Db.new.find ({"Age": {$gt: +}}) #查找age大于22的文档 > Db.new.find ({"Age": {$lt:]}) #查找age小于22的文档 > Db.new.find ({" Age ": {$gte: $}) #查找age大于等于22的文档 > Db.new.find ({" Age ": {$lte:]}) #查找age小于等于22的文档 <pre name=" code "class=" plain ">> Db.new.find ({" Age ": {$lte: $gt:}) #查找age小于等于27, documents greater than 22.

The $type operator is based on the Bson type to retrieve the matching results in the collection.

Types that can be used in MongoDB:

Type Description	Type value
Double	1
String	2
Object	3
Array	4
Binary data	5
Object ID	7
Boolean	8
Date	9
Null	10
Regular expression	11
JavaScript Code	13
Symbol	14
JavaScript Code with scope	15
32-bit integer	16
Timestamp	17
64-bit integer	18
Min Key	255
Max Key	127

>db.new.find ({"Age": {$type: +}}) #查找age为double型的所有数据

Novice MongoDB Learning---(iv) MONGODB conditional operator