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,) - insert a document, optional parameters are: w, wtimeout, jdb.user.insertMany( [objects], ) - 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,) - update the first matching document, optional parameters are: upsert, w, wtimeout, jdb.user.updateMany( filter, update, ) - 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(, ) modifiers .sort({...}) .limit( ) .skip( ) .batchSize( ) - sets the number of docs to return per getMore .collation({...}) .hint({...}) .readConcern( ) .readPref( , ) .count( ) - total # of objects matching query. by default ignores skip,limit .size() - total # of objects cursor would return, honors skip,limit .explain( ) - accepted verbosities are { 'queryPlanner', 'executionStats', 'allPlansExecution'} .min({...}) .max({...}) .maxScan( ) .maxTimeMS( ) .comment( ) .snapshot() .tailable( ) .noCursorTimeout() .allowPartialResults() .returnKey() .showRecordId() - adds a $recordId field to each returned objectCursor methods .toArray() - iterates through docs and returns an array of the results .forEach( ) .map( ) .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,) - delete first matching document, optional parameters are: projection, sort, maxTimeMSdb.user.findOneAndReplace( filter, replacement, ) - replace first matching document, optional parameters are: projection, sort, maxTimeMS, upsert, returnNewDocumentdb.user.findOneAndUpdate( filter, update, ) - 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