Mongodb对集合(表)和数据的CRUD操作

一、集合（对应数据库的表）

1、查看当前库里的所有集合

show collections

2、新建集合

显式创建

db.createCollection("user")

隐式创建

db.user.insert({name:"zhangsan"})

3、删除集合

db.user.dorp()

二、文档（对应数据库中的行）

1、新增（insert、save、insertOne/insertMany）

1.1、使用insert方法新增

db.user.insert({name:"zhangsan",age:20,sex:"boy"})

或者先定义变量再保存变量

lisi={name:"lisi",age:30,sex:"girl",phone:"13999999999"}

db.user.insert(lisi)

1.2、使用save方法新增

db.user.save({name:"xiaoli",age:18,sex:"girl"})

或者先定义变量再保存变量

wangwu={name:"wangwu",age:28,sex:"boy",email:"xxx@xx.com"}

db.user.save(wangwu)

1.3、使用insertOne（单条插入，等同于insert）和insertMany（批量插入）

db.user.insertOne( obj, <optional params> ) - insert a document, optional parameters are: w, wtimeout, j
db.user.insertMany( [objects], <optional params> ) - insert multiple documents, optional parameters are: w, wtimeout, j

2、删

db.user.remove({name:"wangwu"})

db.user.deleteOne({name:"lisi"})

db.user.deleteMany({age:29})

3、改

3.1、save方法

带id的save为更新（只更新一条）

db.user.save({ "_id" : ObjectId("5afbbbc88a20764e0abc31ac"), "name" : "wangwu", "age" : 18, "sex" : "boy", "email" : "2xxx@xx.com" })

3.2、update方法

db.user.update( query, object[, upsert_bool, multi_bool] )

upsert_bool：true表示如果没找到query相关的记录，则插入一条值为obj的记录
muliti_bool: true表示如果query查到多条，则全部更新下

其中局部修改器有2个：修改器： $inc 和 $set。
$set就是赋值的意思，$inc是自增的意思

带过滤条件的全量更新（只更新匹配的第一条）

db.user.update({name:"wangwu"},{"name" : "wangwu", "age" : 28, "sex" : "boy", "email" : "2xxx@xx.com" })

带过滤条件的更新某些字段（只更新匹配的第一条）

db.user.update({name:"wangwu"},{$set:{email:"3xxx@qq.com"}})

查询数据不存在，新增一条

 db.user.update({age:18},{$set:{age:30}},true,false)

db.user.update({age:18},{name:"18girl",age:30},true,false)

根据muliti_bool参数的true和false不同，3.2版本开始引入了单条更新和多条更新的方法

db.user.updateOne( filter, update, <optional params> ) - update the first matching document, optional parameters are: upsert, w, wtimeout, j

db.user.updateMany( filter, update, <optional params> ) - update all matching documents, optional parameters are: upsert, w, wtimeout, j

4、查

db.user.find([query],[fields]) - query is an optional query filter. fields is optional set of fields to return.

find方法如下很多子方法

find(<predicate>, <projection>) modifiers
        .sort({...})
        .limit(<n>)
        .skip(<n>)
        .batchSize(<n>) - sets the number of docs to return per getMore
        .collation({...})
        .hint({...})
        .readConcern(<level>)
        .readPref(<mode>, <tagset>)
        .count(<applySkipLimit>) - total # of objects matching query. by default ignores skip,limit
        .size() - total # of objects cursor would return, honors skip,limit
        .explain(<verbosity>) - accepted verbosities are {'queryPlanner', 'executionStats', 'allPlansExecution'}
        .min({...})
        .max({...})
        .maxScan(<n>)
        .maxTimeMS(<n>)
        .comment(<comment>)
        .snapshot()
        .tailable(<isAwaitData>)
        .noCursorTimeout()
        .allowPartialResults()
        .returnKey()
        .showRecordId() - adds a $recordId field to each returned object

Cursor methods
        .toArray() - iterates through docs and returns an array of the results
        .forEach(<func>)
        .map(<func>)
        .hasNext()
        .next()
        .close()
        .objsLeftInBatch() - returns count of docs left in current batch (when exhausted, a new getMore will be issued)
        .itcount() - iterates through documents and counts them
        .getQueryPlan() - get query plans associated with shape. To get more info on query plans, call getQueryPlan().help().
        .pretty() - pretty print each document, possibly over multiple lines

db.user.findOne([query], [fields], [options], [readConcern])

db.user.findOneAndDelete( filter, <optional params> ) - delete first matching document, optional parameters are: projection, sort, maxTimeMS

db.user.findOneAndReplace( filter, replacement, <optional params> ) - replace first matching document, optional parameters are: projection, sort, maxTimeMS, upsert, returnNewDocument

db.user.findOneAndUpdate( filter, update, <optional params> ) - update first matching document, optional parameters are: projection, sort, maxTimeMS, upsert, returnNewDocument

由于查询比较复杂，特在后面的blog中详细说明