MongoDB快速入门笔记(四)之MongoDB查询文档操作实例代码

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MongoDB简介

MongoDB 是一个基于分布式文件存储的数据库。由 C++ 语言编写。旨在为 WEB 应用提供可扩展的高性能数据存储解决方案。

MongoDB 是一个介于关系数据库和非关系数据库之间的产品,是非关系数据库当中功能最丰富,最像关系数据库的。

下面给大家介绍MongoDB查询文档操作的实例

先把student删除,再重新插入数据

> db.student.drop()
true
> db.student.insert([{ "_id" : 1, "name" : "zhangsan", "age": 27, "sex": 1 }, { "_id" : 2, "name" : "lisi", "age": 27 } ,{ "_id" : 3, "name" : "wangwu", "age": 30 }, { "_id" : 4, "name" : "zhaoliu", "age": 28 }, { "_id" : 5, "name" : "qianliu", "age": 33 }, { "_id" : 6, "name" : "sunba", "age": 32 }])
BulkWriteResult({
"writeErrors" : [ ],
"writeConcernErrors" : [ ],
"nInserted" : 6,
"nUpserted" : 0,
"nMatched" : 0,
"nModified" : 0,
"nRemoved" : 0,
"upserted" : [ ]
})
> db.student.find()
{ "_id" : 1, "name" : "zhangsan", "age" : 27 }
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 3, "name" : "wangwu", "age" : 30 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
{ "_id" : 5, "name" : "qianliu", "age" : 33 }
{ "_id" : 6, "name" : "sunba", "age" : 32 } 

1、查询指定键

db.集合名称.find({查询条件},{指定键})

指定键:1表示显示,0表示不显示,_id默认显示

> db.student.find({},{name:1})
{ "_id" : 1, "name" : "zhangsan" }
{ "_id" : 2, "name" : "lisi" }
{ "_id" : 3, "name" : "wangwu" }
{ "_id" : 4, "name" : "zhaoliu" }
{ "_id" : 5, "name" : "qianliu" }
{ "_id" : 6, "name" : "sunba" }
> db.student.find({},{_id:0, age:0})
{ "name" : "zhangsan", "sex" : 1 }
{ "name" : "lisi" }
{ "name" : "wangwu" }
{ "name" : "zhaoliu" }
{ "name" : "qianliu" }
{ "name" : "sunba" }
> db.student.find({},{_id:0, name:1})
{ "name" : "zhangsan" }
{ "name" : "lisi" }
{ "name" : "wangwu" }
{ "name" : "zhaoliu" }
{ "name" : "qianliu" }
{ "name" : "sunba" } 

2、各种查询方式

$lt:<
$lte:<=
$gt:>
$gte:>=
$ne:!=
> db.student.find({age:{$lt:30}})
{ "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 }
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
> db.student.find({age:{$ne:27}})
{ "_id" : 3, "name" : "wangwu", "age" : 30 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
{ "_id" : 5, "name" : "qianliu", "age" : 33 }
{ "_id" : 6, "name" : "sunba", "age" : 32 } 

$in:包含

$nin:不包含

> db.student.find({age:{$in:[27,28]}})
{ "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 }
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
> db.student.find({age:{$nin:[27,28]}})
{ "_id" : 3, "name" : "wangwu", "age" : 30 }
{ "_id" : 5, "name" : "qianliu", "age" : 33 }
{ "_id" : 6, "name" : "sunba", "age" : 32 } 

$or:或者

> db.student.find({$or:[{age:{$lt:29}}, {name:"sunba"}]})
{ "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 }
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
{ "_id" : 6, "name" : "sunba", "age" : 32 } 

null:空值

> db.student.find({sex: null})
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 3, "name" : "wangwu", "age" : 30 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
{ "_id" : 5, "name" : "qianliu", "age" : 33 }
{ "_id" : 6, "name" : "sunba", "age" : 32 } 

$type:键是某种类型的

double:1
string:2
...

> db.student.insert({_id:7, name:7, age:70})
WriteResult({ "nInserted" : 1 })
> db.student.find({name: {$type: 2}})
{ "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 }
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 3, "name" : "wangwu", "age" : 30 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
{ "_id" : 5, "name" : "qianliu", "age" : 33 }
{ "_id" : 6, "name" : "sunba", "age" : 32 }
> db.student.find({name: {$type: 1}})
{ "_id" : 7, "name" : 7, "age" : 70 } 

正则表达式

> db.student.find({name: /si\b/})
{ "_id" : 2, "name" : "lisi", "age" : 27 } 

db.集合名称.findOne({查询条件},{指定键})
查询出符合条件的第一条数据

> db.student.findOne()
{ "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 } 

db.集合名称.find({查询条件},{指定键}).limit(数字)
查询前几条数据

> db.student.find().limit(3)
{ "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 }
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 3, "name" : "wangwu", "age" : 30 } 

db.集合名称.find({查询条件},{指定键}).skip(数字)
跳过前几条数据

> db.student.find().skip(2)
{ "_id" : 3, "name" : "wangwu", "age" : 30 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
{ "_id" : 5, "name" : "qianliu", "age" : 33 }
{ "_id" : 6, "name" : "sunba", "age" : 32 }
{ "_id" : 7, "name" : 7, "age" : 70 } 

可以使用limit()和skip()实现分页

> db.student.find().skip(0).limit(3)
{ "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 }
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 3, "name" : "wangwu", "age" : 30 }
> db.student.find().skip(3).limit(3)
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
{ "_id" : 5, "name" : "qianliu", "age" : 33 }
{ "_id" : 6, "name" : "sunba", "age" : 32 }
> db.student.find().skip(6).limit(3)
{ "_id" : 7, "name" : 7, "age" : 70 } 

db.集合名称.find().sort({键:数字})
数字为1表示升序,数字为2表示降序

> db.student.find().sort({age:1})
{ "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 }
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
{ "_id" : 3, "name" : "wangwu", "age" : 30 }
{ "_id" : 6, "name" : "sunba", "age" : 32 }
{ "_id" : 5, "name" : "qianliu", "age" : 33 }
{ "_id" : 7, "name" : 7, "age" : 70 }
> db.student.find().sort({age:1, _id:-1})
{ "_id" : 2, "name" : "lisi", "age" : 27 }
{ "_id" : 1, "name" : "zhangsan", "age" : 27, "sex" : 1 }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 }
{ "_id" : 3, "name" : "wangwu", "age" : 30 }
{ "_id" : 6, "name" : "sunba", "age" : 32 }
{ "_id" : 5, "name" : "qianliu", "age" : 33 }
{ "_id" : 7, "name" : 7, "age" : 70 } 

以上内容是小编给大家介绍的MongoDB快速入门笔记(四)之MongoDB查询文档操作实例代码,希望对大家有所帮助!


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