MongoDB基本操作

MongoDB 基本操作

当前文档基于 MongoDB server version: 4.0.20

0. MongoDB 特性

用MySQL 和 MongoDB 做比较

1. 数据库操作

在mongoDB中, 若数据库不存在，那么只有在库中向集合插入数据的时候才会创建

1.1 用法

查看数据库

show dbs

指定数据库

use Database

查看当前数据库

默认情况下，当前数据库是test

db

删除数据库

在操作此步骤之前，应当使用 db 确认一下库名

执行dropDatabase() 操作后，当前选择的数据库依然是这个库，只不过是在内存中而已。

db.dropDatabase()

查看数据库版本

db.version()

查看当前库统计信息

db.stats()

1.2 例子

查看当前有哪些数据库

> show dbs admin 0.000GB blogSystem 0.000GB config 0.000GB local 0.000GB >

查看当前数据库

> db test >

创建一个数据库并且查看

> use LearnDB switched to db LearnDB > > db LearnDB >

删除数据库

> db.dropDatabase() { "ok" : 1 } >

查看数据库版本

> db.version() 4.0.20 >

查看当前库统计信息

> db.stats() { "db" : "LearnDB", "collections" : 0, "views" : 0, "objects" : 0, "avgObjSize" : 0, "dataSize" : 0, "storageSize" : 0, "numExtents" : 0, "indexes" : 0, "indexSize" : 0, "fileSize" : 0, "fsUsedSize" : 0, "fsTotalSize" : 0, "ok" : 1 } >

2. 集合操作

默认情况下，mongo在插入文档的时候，集合默认会被创建

2.1 用法

查看当前库的集合

show Collections

插入单条数据

db.CollectionName.insertOne()

插入多条数据

db.CollectionName.insertMany()

删除集合

db.CollectionName.drop()

修改集合名称

db.CollectionName.renameCollection()

创建集合

db.createCollection()

2.2 例子

插入单条数据

> db.stu_info.insertOne({"std_name":"小明","sex":"男","reg_time":Date()}) { "acknowledged" : true, "insertedId" : ObjectId("61d6b4afa5a7b57ea8e0a9db") }

查看当前库的集合

> show collections stu_info >

插入多条数据

> db.stu_info.insertMany([{"std_name":"小刚","sex":"男","reg_time":Date()},{"std_name":"小红","sex":"女","reg_time":Date()}]) { "acknowledged" : true, "insertedIds" : [ ObjectId("61d6b59da5a7b57ea8e0a9dc"), ObjectId("61d6b59da5a7b57ea8e0a9dd") ] } >

删除集合

> db.stu_info.drop() true >

修改集合名称

> db.stu_info.renameCollection("stuInfo") { "ok" : 1 } > show collections stuInfo >

创建集合

默认情况下，向集合中插入数据，会默认创建，还有一种情况，是设置集合为 容量上限模式 ，则需要提前创建

语法

db.createCollection(, { capped: , autoIndexId: , size: , max: , storageEngine: , validator: , validationLevel: , validationAction: , indexOptionDefaults: , viewOn: , pipeline: , collation: , writeConcern: } )

name: 集合名称 capped: 若为true,则创建 有上限模式 的集合 size: 设置上限的最大大小，以字节为单位，若达到最大值，则会删除旧文档 max: 允许最大文档数，当同时设置 size 和 max ， 则 size 优先级 大于 max

创建有上限的集合, 允许的条数为5条, 最大容量为1G

> db.createCollection("std_log",{"capped":true , "size": 1073741824 , "max": 5}) { "ok" : 1 } >

测试插入数据

可以发现，插入超过5条后，新插入的数据，会删除旧文档，然后插入新文档

> db.std_log.insertMany([{"id":1,"status":true,"time":Date()},{"id":2,"status":false,"time":Date()},{"id":3,"status":true,"time":Date()},{"id":4,"status":true,"time":Date()},{"id":5,"status":false,"time":Date()}]) { "acknowledged" : true, "insertedIds" : [ ObjectId("61d6c44da5a7b57ea8e0aa01"), ObjectId("61d6c44da5a7b57ea8e0aa02"), ObjectId("61d6c44da5a7b57ea8e0aa03"), ObjectId("61d6c44da5a7b57ea8e0aa04"), ObjectId("61d6c44da5a7b57ea8e0aa05") ] } > db.std_log.find() { "_id" : ObjectId("61d6c44da5a7b57ea8e0aa01"), "id" : 1, "status" : true, "time" : "Thu Jan 06 2022 18:28:29 GMT+0800 (CST)" } { "_id" : ObjectId("61d6c44da5a7b57ea8e0aa02"), "id" : 2, "status" : false, "time" : "Thu Jan 06 2022 18:28:29 GMT+0800 (CST)" } { "_id" : ObjectId("61d6c44da5a7b57ea8e0aa03"), "id" : 3, "status" : true, "time" : "Thu Jan 06 2022 18:28:29 GMT+0800 (CST)" } { "_id" : ObjectId("61d6c44da5a7b57ea8e0aa04"), "id" : 4, "status" : true, "time" : "Thu Jan 06 2022 18:28:29 GMT+0800 (CST)" } { "_id" : ObjectId("61d6c44da5a7b57ea8e0aa05"), "id" : 5, "status" : false, "time" : "Thu Jan 06 2022 18:28:29 GMT+0800 (CST)" } > > db.std_log.insertOne({"id":6,"status":false,"time":Date()}) { "acknowledged" : true, "insertedId" : ObjectId("61d6c4b9a5a7b57ea8e0aa07") } > db.std_log.find() { "_id" : ObjectId("61d6c44da5a7b57ea8e0aa02"), "id" : 2, "status" : false, "time" : "Thu Jan 06 2022 18:28:29 GMT+0800 (CST)" } { "_id" : ObjectId("61d6c44da5a7b57ea8e0aa03"), "id" : 3, "status" : true, "time" : "Thu Jan 06 2022 18:28:29 GMT+0800 (CST)" } { "_id" : ObjectId("61d6c44da5a7b57ea8e0aa04"), "id" : 4, "status" : true, "time" : "Thu Jan 06 2022 18:28:29 GMT+0800 (CST)" } { "_id" : ObjectId("61d6c44da5a7b57ea8e0aa05"), "id" : 5, "status" : false, "time" : "Thu Jan 06 2022 18:28:29 GMT+0800 (CST)" } { "_id" : ObjectId("61d6c4b9a5a7b57ea8e0aa07"), "id" : 6, "status" : false, "time" : "Thu Jan 06 2022 18:30:17 GMT+0800 (CST)" } >

3. 查询操作

3.1 用法

查询集合文档条数

db.CollectionNmae.count()

普通查询

db.CollectionName.find()

格式化显示

db.CollectionName.find().pretty()

比较查询

等于

db.CollectionName.find({k:v})

不等于

db.CollectionName.find({k:{$ne: v})

大于

db.CollectionName.find({k:{$gt: v})

小于

db.CollectionName.find({k:{$lt: v})

大于或等于

db.CollectionName.find({k:{$lte: v})

小于或等于

db.CollectionName.find({k:{$gte: v})

and | or 查询

and

db.CollectionName.find({k:v,k1:v1})

or

db.CollectionName.find({$or:[{k1:v1},{k2:v2}]})

and 和 or 联合查询

db.CollectionName.find({k:v,$or:[{k1:v1},{k2:v2}]})

排序查询

db.CollectionName.find().sort({k:1})

指定返回行数查询

db.CollectionName.find().limit()

db.CollectionName.find().skip()

指定返回域

db.CollectionName.find({k:v},{k1:1,k2:1})

只返回一条

db.CollectionName.findOne({k:v})

只返回一条并且删除该数据

db.CollectionName.findOneAndDelete({k:v})

3.2 例子

数据准备

> use LearnDB switched to db LearnDB > > db.dropDatabase() { "dropped" : "LearnDB", "ok" : 1 } > > > db.stu_info.insertMany([ ... {"name": "小明" , "sex": "男" , "score1": 98 , "score2": 60, "score3": 79 , "score5": 101 , "classID: " : 1}, ... {"name": "小红" , "sex": "女" , "score1": 100 , "score2": 100, "score3": 100 , "score5": 80 , "classID: " : 3}, ... {"name": "小赵" , "sex": "女" , "score1": 80 , "score2": 79, "score3": 33 , "score5": 55 , "classID: " : 3}, ... {"name": "小钱" , "sex": "男" , "score1": 89 , "score2": 36, "score3": 102 , "score5": 65 , "classID: " : 5}, ... {"name": "小李" , "sex": "女" , "score1": 53 , "score2": 91, "score3": 34 , "score5": 19 , "classID: " : 9}, ... {"name": "小王" , "sex": "女" , "score1": 100 , "score2": 100, "score3": 100 , "score5": 99 , "classID: " : 1}, ... {"name": "小周" , "sex": "女" , "score1": 99 , "score2": 94, "score3": 92 , "score5": 90 , "classID: " : 6} ... ]) { "acknowledged" : true, "insertedIds" : [ ObjectId("61d6cac2a5a7b57ea8e0aa08"), ObjectId("61d6cac2a5a7b57ea8e0aa09"), ObjectId("61d6cac2a5a7b57ea8e0aa0a"), ObjectId("61d6cac2a5a7b57ea8e0aa0b"), ObjectId("61d6cac2a5a7b57ea8e0aa0c"), ObjectId("61d6cac2a5a7b57ea8e0aa0d"), ObjectId("61d6cac2a5a7b57ea8e0aa0e") ] } >

查询集合文档条数

> db.stu_info.count() 7 >

普通查询

mongo shell 默认只返回10条，超过10条 需要 根据提示往下翻页

> db.stu_info.find() { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa08"), "name" : "小明", "sex" : "男", "score1" : 98, "score2" : 60, "score3" : 79, "score5" : 101, "classID: " : 1 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0a"), "name" : "小赵", "sex" : "女", "score1" : 80, "score2" : 79, "score3" : 33, "score5" : 55, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0b"), "name" : "小钱", "sex" : "男", "score1" : 89, "score2" : 36, "score3" : 102, "score5" : 65, "classID: " : 5 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0c"), "name" : "小李", "sex" : "女", "score1" : 53, "score2" : 91, "score3" : 34, "score5" : 19, "classID: " : 9 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0e"), "name" : "小周", "sex" : "女", "score1" : 99, "score2" : 94, "score3" : 92, "score5" : 90, "classID: " : 6 } >

指定返回行数查询

查询2个文档

> db.stu_info.find().limit(2) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa08"), "name" : "小明", "sex" : "男", "score1" : 98, "score2" : 60, "score3" : 79, "score5" : 101, "classID: " : 1 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } >

跳过第1个文档，查询1个文档

> db.stu_info.find().skip(1).limit(1) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } >

格式化显示

> db.stu_info.find().pretty().limit(2) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa08"), "name" : "小明", "sex" : "男", "score1" : 98, "score2" : 60, "score3" : 79, "score5" : 101, "classID: " : 1 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } >

比较查询

等于： 查询 name 等于 小明 的文档

> db.stu_info.find({"name":"小明"}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa08"), "name" : "小明", "sex" : "男", "score1" : 98, "score2" : 60, "score3" : 79, "score5" : 101, "classID: " : 1 } >

不等于： 查询 name 不等于 小明 的文档，并且取出第一个

> db.stu_info.find({"name":{$ne:"小明"}}).limit(1).pretty() { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } >

大于: 查询 socre3 大于100 的文档

> db.stu_info.find({"score3":{$gt:100}}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0b"), "name" : "小钱", "sex" : "男", "score1" : 89, "score2" : 36, "score3" : 102, "score5" : 65, "classID: " : 5 } >

小于: 查询 socre1 小于80 的文档

> db.stu_info.find({"score1":{$lt:80}}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0c"), "name" : "小李", "sex" : "女", "score1" : 53, "score2" : 91, "score3" : 34, "score5" : 19, "classID: " : 9 } >

大于或等于：查询 socre3 大于等于 100 的文档

> db.stu_info.find({"score3":{$gte:100}}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0b"), "name" : "小钱", "sex" : "男", "score1" : 89, "score2" : 36, "score3" : 102, "score5" : 65, "classID: " : 5 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1 } >

大于或等于：查询 socre1 小于等于 80 的文档

> db.stu_info.find({"score1":{$lte:80}}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0a"), "name" : "小赵", "sex" : "女", "score1" : 80, "score2" : 79, "score3" : 33, "score5" : 55, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0c"), "name" : "小李", "sex" : "女", "score1" : 53, "score2" : 91, "score3" : 34, "score5" : 19, "classID: " : 9 } >

and | or 查询

and：查询 score1等于100 score2等于100 的文档

> db.stu_info.find({"score1":100,"score2":100}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1 } >

**or： 查询socre1 等于 53 或者score2等于 94 的文档 **

> db.stu_info.find({$or:[{"score1":53},{"score2":94}]}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0c"), "name" : "小李", "sex" : "女", "score1" : 53, "score2" : 91, "score3" : 34, "score5" : 19, "classID: " : 9 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0e"), "name" : "小周", "sex" : "女", "score1" : 99, "score2" : 94, "score3" : 92, "score5" : 90, "classID: " : 6 } >

and 和 or 联合查询 ：查询sex 等于 男 ，在此基础上 查询 score1 等于 99 或者 score1 等于 91 的文档

> db.stu_info.find({"sex":"女",$or:[{"score1":99},{"score2":91}]}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0c"), "name" : "小李", "sex" : "女", "score1" : 53, "score2" : 91, "score3" : 34, "score5" : 19, "classID: " : 9 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0e"), "name" : "小周", "sex" : "女", "score1" : 99, "score2" : 94, "score3" : 92, "score5" : 90, "classID: " : 6 } >

排序查询： 对score1进行升序和降序排序

1: 升序

-1: 降序

> db.stu_info.find().sort({"score1":1}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0c"), "name" : "小李", "sex" : "女", "score1" : 53, "score2" : 91, "score3" : 34, "score5" : 19, "classID: " : 9 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0a"), "name" : "小赵", "sex" : "女", "score1" : 80, "score2" : 79, "score3" : 33, "score5" : 55, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0b"), "name" : "小钱", "sex" : "男", "score1" : 89, "score2" : 36, "score3" : 102, "score5" : 65, "classID: " : 5 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa08"), "name" : "小明", "sex" : "男", "score1" : 98, "score2" : 60, "score3" : 79, "score5" : 101, "classID: " : 1 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0e"), "name" : "小周", "sex" : "女", "score1" : 99, "score2" : 94, "score3" : 92, "score5" : 90, "classID: " : 6 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1 } >

> db.stu_info.find().sort({"score1":-1}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0e"), "name" : "小周", "sex" : "女", "score1" : 99, "score2" : 94, "score3" : 92, "score5" : 90, "classID: " : 6 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa08"), "name" : "小明", "sex" : "男", "score1" : 98, "score2" : 60, "score3" : 79, "score5" : 101, "classID: " : 1 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0b"), "name" : "小钱", "sex" : "男", "score1" : 89, "score2" : 36, "score3" : 102, "score5" : 65, "classID: " : 5 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0a"), "name" : "小赵", "sex" : "女", "score1" : 80, "score2" : 79, "score3" : 33, "score5" : 55, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0c"), "name" : "小李", "sex" : "女", "score1" : 53, "score2" : 91, "score3" : 34, "score5" : 19, "classID: " : 9 } >

指定返回域: 获取name 和 score1 域的数据

> db.stu_info.find({},{"name":1,"score1":1}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa08"), "name" : "小明", "score1" : 98 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "score1" : 100 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0a"), "name" : "小赵", "score1" : 80 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0b"), "name" : "小钱", "score1" : 89 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0c"), "name" : "小李", "score1" : 53 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "score1" : 100 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0e"), "name" : "小周", "score1" : 99 } >

只返回一条：查询socre1小于等于100的数据，仅返回一条

> db.stu_info.findOne({"score1": {$lte: 100}}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa08"), "name" : "小明", "sex" : "男", "score1" : 98, "score2" : 60, "score3" : 79, "score5" : 101, "classID: " : 1 } >

只返回一条并且删除该数据：查询socre1小于等于100的数据，仅返回一条，并且删除

> db.stu_info.findOneAndDelete({"score1":{$lte:100}}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa08"), "name" : "小明", "sex" : "男", "score1" : 98, "score2" : 60, "score3" : 79, "score5" : 101, "classID: " : 1 } > db.stu_info.findOne({"name":"小明"}) null >

4. 更新操作

4.1 用法

更新一个文档

db.CollectionName.updateOne()

更新多个文档

db.CollectionName.updateOne()

db.CollectionName.updateMany()

4.2 例子

只更新一个文档：将 score1 为 100 的文档 新增一个classID 为 16

> db.stu_info.find({"score1":100}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1 } > > db.stu_info.updateOne({"score1":100},{$set:{"classID":16}}) { "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 } > > db.stu_info.find({"score1":100}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3, "classID" : 16 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1 } >

更新多个文档

更新所有文档：将 score1 为 100 的文档 设置 新增/设置一个 classID 为 21

> db.stu_info.find({"score1":100}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3, "classID" : 16 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1 } > > db.stu_info.updateMany({"score1":100},{$set:{"classID":21}}) { "acknowledged" : true, "matchedCount" : 2, "modifiedCount" : 2 } > > db.stu_info.find({"score1":100}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3, "classID" : 21 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1, "classID" : 21 } >

5. 删除操作

5.1 用法

删除一条文档

db.CollectionName.deleteOne()

删除多条文档

db.CollectionName.deleteMany()

5.2 例子

删除一条文档：删除socre1为100的一条文档

> db.stu_info.find({"score1":100}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa09"), "name" : "小红", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 80, "classID: " : 3, "classID" : 21 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1, "classID" : 21 } > > db.stu_info.deleteOne({"score1":100}) { "acknowledged" : true, "deletedCount" : 1 } > > db.stu_info.find({"score1":100}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1, "classID" : 21 } >

删除多条文档: 删除socre1小于90的所有文档

> db.stu_info.find({"score1":{$lt:90}}) { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0a"), "name" : "小赵", "sex" : "女", "score1" : 80, "score2" : 79, "score3" : 33, "score5" : 55, "classID: " : 3 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0b"), "name" : "小钱", "sex" : "男", "score1" : 89, "score2" : 36, "score3" : 102, "score5" : 65, "classID: " : 5 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0c"), "name" : "小李", "sex" : "女", "score1" : 53, "score2" : 91, "score3" : 34, "score5" : 19, "classID: " : 9 } > > db.stu_info.deleteMany({"score1":{$lt:90}}); { "acknowledged" : true, "deletedCount" : 3 } > > db.stu_info.find({"score1":{$lt:90}}) >

6. 索引操作

6.1 用法

查询集合所有

db.CollectionName.getIndexes()

创建索引

db.CollectionName.createIndex()

删除集合除_id以外的所有索引

db.CollectionName.dropIndexes()

删除索引

db.CollectionName.dropIndex()

6.2 例子

查询集合所有

> db.stu_info.getIndexes() [ { "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "LearnDB.stu_info" } ] >

创建索引

语法

db.collection.createIndex( { "a": 1 }, { unique: true, sparse: true, expireAfterSeconds: 3600 } )

可选参数

background: bool类型 为true则在后台构建索引，默认为false unique: bool类型 为true则创建唯一索引，默认为false name: string类型 索引名称, 如果未指定，mongodb将通过索引字段和排序来生成索引名称 sparse: bool类型 为true则对文档不存在字段数据不启用索引，默认为false expireAfterSeconds: 整形 指定一个值(以秒为单位)作为TTL，设置生存时间

例子1： 给集合stu_info sex name 增加唯一索引

> db.stu_info.getIndexes() [ { "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "LearnDB.stu_info" } ] > > db.stu_info.createIndex({"name":1} , {"background":true,"unique":true , "name":"stu_info_name"}) { "createdCollectionAutomatically" : false, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 } > > db.stu_info.getIndexes() [ { "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "LearnDB.stu_info" }, { "v" : 2, "unique" : true, "key" : { "name" : 1 }, "name" : "stu_info_name", "ns" : "LearnDB.stu_info", "background" : true } ] >

尝试新增相同name的文档

> db.stu_info.find() { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0d"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1, "classID" : 21 } { "_id" : ObjectId("61d6cac2a5a7b57ea8e0aa0e"), "name" : "小周", "sex" : "女", "score1" : 99, "score2" : 94, "score3" : 92, "score5" : 90, "classID: " : 6 } > > db.stu_info.insertMany([ {"name": "小王" , "sex": "女" , "score1": 100 , "score2": 100, "score3": 100 , "score5": 99 , "classID: " : 1} ]) 2022-01-08T10:56:46.475+0800 E QUERY [js] BulkWriteError: write error at item 0 in bulk operation : BulkWriteError({ "writeErrors" : [ { "index" : 0, "code" : 11000, "errmsg" : "E11000 duplicate key error collection: LearnDB.stu_info index: stu_info_name dup key: { : \"小王\" }", "op" : { "_id" : ObjectId("61d8fd6e3a0069c72ccea003"), "name" : "小王", "sex" : "女", "score1" : 100, "score2" : 100, "score3" : 100, "score5" : 99, "classID: " : 1 } } ], "writeConcernErrors" : [ ], "nInserted" : 0, "nUpserted" : 0, "nMatched" : 0, "nModified" : 0, "nRemoved" : 0, "upserted" : [ ] }) BulkWriteError@src/mongo/shell/bulk_api.js:369:48 BulkWriteResult/this.toError@src/mongo/shell/bulk_api.js:333:24 Bulk/this.execute@src/mongo/shell/bulk_api.js:1173:1 DBCollection.prototype.insertMany@src/mongo/shell/crud_api.js:314:5 @(shell):1:1 >

删除索引：删除stu_info name 索引

> db.stu_info.getIndexes() [ { "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "LearnDB.stu_info" }, { "v" : 2, "unique" : true, "key" : { "name" : 1 }, "name" : "stu_info_name", "ns" : "LearnDB.stu_info", "background" : true } ] > > db.stu_info.dropIndex("stu_info_name") { "nIndexesWas" : 2, "ok" : 1 } > > db.stu_info.getIndexes() [ { "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "LearnDB.stu_info" } ] >

完

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