MongoDB $关键字 关系比较符号 $lt $lte $gt $gte $ne

 关系比较符：
   小于：$lt
   小于或等于：$lte
   大于：$gt
   大于或等于：$gte
   不等于：$ne
   属于：$in

查询中常见的 等于 大于 小于 大于等于 小于等于

等于 : 在MongoDB中什么字段等于什么值其实就是 " : " 来搞定 比如 "name" : "jack"

"name" : "jack"

> db.user.find()
{ "_id" : ObjectId("5ca7a4b0219efd687462f965"), "id" : 1, "name" : "jack", "age" : 73 }
{ "_id" : ObjectId("5ca7a4b7219efd687462f966"), "id" : 2, "name" : "mike", "age" : 84, "gender" : "男" }
{ "_id" : ObjectId("5ca7a4c4219efd687462f967"), "id" : 3, "name" : "peter", "age" : 21 }
{ "_id" : ObjectId("5ca7a4c4219efd687462f968"), "id" : 4, "name" : "xiaogang", "age" : 13, "hobby" : [ "羽毛球", "篮球", "足球" ] }
{ "_id" : ObjectId("5ca7a4c4219efd687462f969"), "id" : 5, "name" : "ben", "age" : 24 }
{ "_id" : ObjectId("5ca7a505219efd687462f96a"), "id" : 6, "name" : "Mary", "age" : 84, "gender" : "男" }

小于 : 在MongoDB中的 小于 < 号 我们用 : $lt  比如 :  "age" : { $lt : 73 } 就是 得到 "age" 小于 73 的数据

> db.user.find({age:{$lt:73}})
{ "_id" : ObjectId("5ca7a4c4219efd687462f967"), "id" : 3, "name" : "peter", "age" : 21 }
{ "_id" : ObjectId("5ca7a4c4219efd687462f968"), "id" : 4, "name" : "xiaogang", "age" : 13, "hobby" : [ "羽毛球", "篮球", "足球" ] }
{ "_id" : ObjectId("5ca7a4c4219efd687462f969"), "id" : 5, "name" : "ben", "age" : 24 }

大于 : 在MongoDB中的 大于 > 号 我们用 : $gt  比如 :  "age" : { $gt : 19 } 就是 得到 "age" 大于 19 的数据

> db.user.find({age:{$gt:19}})
{ "_id" : ObjectId("5ca7a4b0219efd687462f965"), "id" : 1, "name" : "jack", "age" : 73 }
{ "_id" : ObjectId("5ca7a4b7219efd687462f966"), "id" : 2, "name" : "mike", "age" : 84, "gender" : "男" }
{ "_id" : ObjectId("5ca7a4c4219efd687462f967"), "id" : 3, "name" : "peter", "age" : 21 }
{ "_id" : ObjectId("5ca7a4c4219efd687462f969"), "id" : 5, "name" : "ben", "age" : 24 }
{ "_id" : ObjectId("5ca7a505219efd687462f96a"), "id" : 6, "name" : "Mary", "age" : 84, "gender" : "男" }

大于等于 : 在MongoDB中的 大于等于 >= 号 我们用 : $gte  比如 :  "age" : { $gte : 13 } 就是 得到 "age" 大于等于 13 的数据

> db.user.find({age:{$gte:13}})
{ "_id" : ObjectId("5ca7a4b0219efd687462f965"), "id" : 1, "name" : "jack", "age" : 73 }
{ "_id" : ObjectId("5ca7a4b7219efd687462f966"), "id" : 2, "name" : "mike", "age" : 84, "gender" : "男" }
{ "_id" : ObjectId("5ca7a4c4219efd687462f967"), "id" : 3, "name" : "peter", "age" : 21 }
{ "_id" : ObjectId("5ca7a4c4219efd687462f968"), "id" : 4, "name" : "xiaogang", "age" : 13, "hobby" : [ "羽毛球", "篮球", "足球" ] }
{ "_id" : ObjectId("5ca7a4c4219efd687462f969"), "id" : 5, "name" : "ben", "age" : 24 }
{ "_id" : ObjectId("5ca7a505219efd687462f96a"), "id" : 6, "name" : "Mary", "age" : 84, "gender" : "男" }

小于等于 : 在MongoDB中的 小于等于 <= 号 我们用 : $lte  比如 :  "age" : { $lte : 73 } 就是 得到 "age" 小于等于 73 的数据

> db.user.find({age:{$lte:73}})
{ "_id" : ObjectId("5ca7a4b0219efd687462f965"), "id" : 1, "name" : "jack", "age" : 73 }
{ "_id" : ObjectId("5ca7a4c4219efd687462f967"), "id" : 3, "name" : "peter", "age" : 21 }
{ "_id" : ObjectId("5ca7a4c4219efd687462f968"), "id" : 4, "name" : "xiaogang", "age" : 13, "hobby" : [ "羽毛球", "篮球", "足球" ] }
{ "_id" : ObjectId("5ca7a4c4219efd687462f969"), "id" : 5, "name" : "ben", "age" : 24 }

不等于：$ne
把age不等于73的所有数据显示

> db.user.find({age:{$ne:73} }  )
{ "_id" : ObjectId("5ca7a4b7219efd687462f966"), "id" : 2, "name" : "mike", "age" : 84, "gender" : "男" }
{ "_id" : ObjectId("5ca7a4c4219efd687462f967"), "id" : 3, "name" : "peter", "age" : 21 }
{ "_id" : ObjectId("5ca7a4c4219efd687462f968"), "id" : 4, "name" : "xiaogang", "age" : 13, "hobby" : [ "羽毛球", "篮球", "足球" ] }
{ "_id" : ObjectId("5ca7a4c4219efd687462f969"), "id" : 5, "name" : "ben", "age" : 24 }
{ "_id" : ObjectId("5ca7a505219efd687462f96a"), "id" : 6, "name" : "Mary", "age" : 84, "gender" : "男" }