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MongoDB快速入门笔记(四)之MongoDB查询文档操作实例代码_MongoDB_
2023-05-27
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简介 MongoDB快速入门笔记(四)之MongoDB查询文档操作实例代码_MongoDB_
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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