MongoDB ÃüÁî¼Ç¼

> help												 ¹ØÓÚmongodbÖ÷Òª·½·¨µÄ°ïÖú
	db.help()                    ¹ØÓÚÊý¾Ý¿â·½·¨µÄ°ïÖú
	db.mycoll.help()             ¹ØÓÚÊý¾Ý¿â±í·½·¨µÄ°ïÖú
	sh.help()                    ·ÖƬ·½·¨µÄ°ïÖú
	rs.help()                    ¸±±¾¼¯·½·¨µÄ°ïÖú
	help admin                   ÐÐÕþ°ïÖú
	help connect                 Á¬½Óµ½Êý¾Ý¿âµÄ°ïÖú
	help keys                    ¼üµÄ¿ì½Ý·½Ê½
	help misc                    misc things to know
	help mr                      mapreduce£¨Ò»ÖÖ·Ö²¼Ê½²¢Ðбà³ÌÄ£ÐÍ£©

	show dbs                     չʾËùÓÐÊý¾Ý¿âµÄÃû³Æ
	show collections             չʾµ±Ç°Êý¾Ý¿âµÄËùÓм¯ºÏ£¨±í£©Ãû³Æ
	show users                   չʾµ±Ç°Êý¾Ý¿âµÄËùÓÐÓû§
	show profile                 ÏÔʾʱ¼äΪ>= 1msµÄ×î½üµÄsystem.profileÌõÄ¿
	show logs                    ÏÔʾ¿É·ÃÎʵÄlogÃû³Æ
	show log [name]              ´òÓ¡³öÄÚ´æÖÐÈÕÖ¾µÄ×îºóÒ»¶Î£¬globalÊÇĬÈÏÖµ
	use <db_name>                ÉèÖõ±Ç°Êý¾Ý¿â
	db.mycoll.find()             ²éѯ¼¯ºÏmycollÖÐËùÓеļǼ
	db.mycoll.find( { a : 1 } )  ²éѯ¼¯ºÏmycollÖеļǼ£¬Ö»²éѯÂú×ãÌõ¼þa=1µÄ¼Ç¼
	it                           ×îºóÒ»ÐÐÇóÖµµÄ½á¹û;ÓÃÓÚ½øÒ»²½µü´ú£¨Ä¿Ç°²»ÖªµÀÔÚÄÄʹÓã©
	DBQuery.shellBatchSize = x   ÉèÖÃshellÉÏÏÔʾµÄÏîÄ¿µÄĬÈÏÊýÁ¿£¨Ä¿Ç°²»ÖªµÀÔÚÄÄʹÓã©
	exit                         Í˳ömongo shell

> db.help()
DB methods:
	db.adminCommand(nameOrDocument) - Çл»µ½'admin' db£¬²¢ÔËÐÐÃüÁî [Ö»µ÷Óà db.runCommand(...)]£¨Ä¿Ç°²»ÖªµÀÔÚÄÄʹÓã©
	db.aggregate([pipeline], {options}) - ¶Ô¸ÃÊý¾Ý¿âÖ´ÐÐÎÞ¼¯ºÏ¾ÛºÏ;·µ»ØÒ»¸öÖ¸Õ루Ŀǰ²»ÖªµÀÔÚÄÄʹÓã©
	db.auth(username, password)£¨Ä¿Ç°²»ÖªµÀÔÚÄÄʹÓã©
	db.cloneDatabase(fromhost) - will only function with MongoDB 4.0 and below
	db.commandHelp(name) returns the help for the command
	db.copyDatabase(fromdb, todb, fromhost) - will only function with MongoDB 4.0 and below
	db.createCollection(name, {size: ..., capped: ..., max: ...})
	db.createUser(userDocument)
	db.createView(name, viewOn, [{$operator: {...}}, ...], {viewOptions})
	db.currentOp() displays currently executing operations in the db
	db.dropDatabase(writeConcern)
	db.dropUser(username)
	db.eval() - deprecated
	db.fsyncLock() flush data to disk and lock server for backups
	db.fsyncUnlock() unlocks server following a db.fsyncLock()
	db.getCollection(cname) same as db['cname'] or db.cname
	db.getCollectionInfos([filter]) - returns a list that contains the names and options of the db's collections
	db.getCollectionNames()
	db.getLastError() - just returns the err msg string
	db.getLastErrorObj() - return full status object
	db.getLogComponents()
	db.getMongo() get the server connection object
	db.getMongo().setSlaveOk() allow queries on a replication slave server
	db.getName()
	db.getProfilingLevel() - deprecated
	db.getProfilingStatus() - returns if profiling is on and slow threshold
	db.getReplicationInfo()
	db.getSiblingDB(name) get the db at the same server as this one
	db.getWriteConcern() - returns the write concern used for any operations on this db, inherited from server object if set
	db.hostInfo() get details about the server's host
	db.isMaster() check replica primary status
	db.killOp(opid) kills the current operation in the db
	db.listCommands() lists all the db commands
	db.loadServerScripts() loads all the myscripts in db.system.js
	db.logout()
	db.printCollectionStats()
	db.printReplicationInfo()
	db.printShardingStatus()
	db.printSlaveReplicationInfo()
	db.resetError()
	db.runCommand(cmdObj) run a database command.  if cmdObj is a string, turns it into {cmdObj: 1}
	db.serverStatus()
	db.setLogLevel(level,<component>)
	db.setProfilingLevel(level,slowms) 0=off 1=slow 2=all
	db.setVerboseShell(flag) display extra information in shell output
	db.setWriteConcern(<write concern doc>) - sets the write concern for writes to the db
	db.shutdownServer()
	db.stats()
	db.unsetWriteConcern(<write concern doc>) - unsets the write concern for writes to the db
	db.version() current version of the server
	db.watch() - opens a change stream cursor for a database to report on all  changes to its non-system collections.

> db.demo.help()
DBCollection help
	db.demo.find().help() - չʾ DBCursor ·½·¨°ïÖú
	db.demo.bulkWrite( operations, <optional params> ) - bulk execute write operations, optional parameters are: w, wtimeout, j
	db.demo.count( query = {}, <optional params> ) - ¼ÆËãÆ¥Åä²éѯµÄÎĵµÊýÁ¿£¬¿ÉÑ¡²ÎÊýÓÐ:limit¡¢skip¡¢hint¡¢maxTimeMS
	db.demo.countDocuments( query = {}, <optional params> ) - count the number of documents that matches the query, optional parameters are: limit, skip, hint, maxTimeMS
	db.demo.estimatedDocumentCount( <optional params> ) - estimate the document count using collection metadata, optional parameters are: maxTimeMS
	db.demo.convertToCapped(maxBytes) - calls {convertToCapped:'demo', size:maxBytes}} command
	db.demo.createIndex(keypattern[,options])
	db.demo.createIndexes([keypatterns], <options>)
	db.demo.dataSize()
	db.demo.deleteOne( filter, <optional params> ) - delete first matching document, optional parameters are: w, wtimeout, j
	db.demo.deleteMany( filter, <optional params> ) - delete all matching documents, optional parameters are: w, wtimeout, j
	db.demo.distinct( key, query, <optional params> ) - e.g. db.demo.distinct( 'x' ), optional parameters are: maxTimeMS
	db.demo.drop() drop the collection
	db.demo.dropIndex(index) - e.g. db.demo.dropIndex( "indexName" ) or db.demo.dropIndex( { "indexKey" : 1 } )
	db.demo.hideIndex(index) - e.g. db.demo.hideIndex( "indexName" ) or db.demo.hideIndex( { "indexKey" : 1 } )
	db.demo.unhideIndex(index) - e.g. db.demo.unhideIndex( "indexName" ) or db.demo.unhideIndex( { "indexKey" : 1 } )
	db.demo.dropIndexes()
	db.demo.ensureIndex(keypattern[,options]) - DEPRECATED, use createIndex() instead
	db.demo.explain().help() - show explain help
	db.demo.reIndex()
	db.demo.find([query],[fields]) - query is an optional query filter. fields is optional set of fields to return.
	                                              e.g. db.demo.find( {x:77} , {name:1, x:1} )
	db.demo.find(...).count()
	db.demo.find(...).limit(n)
	db.demo.find(...).skip(n)
	db.demo.find(...).sort(...)
	db.demo.findOne([query], [fields], [options], [readConcern])
	db.demo.findOneAndDelete( filter, <optional params> ) - delete first matching document, optional parameters are: projection, sort, maxTimeMS
	db.demo.findOneAndReplace( filter, replacement, <optional params> ) - replace first matching document, optional parameters are: projection, sort, maxTimeMS, upsert, returnNewDocument
	db.demo.findOneAndUpdate( filter, <update object or pipeline>, <optional params> ) - update first matching document, optional parameters are: projection, sort, maxTimeMS, upsert, returnNewDocument
	db.demo.getDB() get DB object associated with collection
	db.demo.getPlanCache() get query plan cache associated with collection
	db.demo.getIndexes()
	db.demo.insert(obj)
	db.demo.insertOne( obj, <optional params> ) - insert a document, optional parameters are: w, wtimeout, j
	db.demo.insertMany( [objects], <optional params> ) - insert multiple documents, optional parameters are: w, wtimeout, j
	db.demo.mapReduce( mapFunction , reduceFunction , <optional params> )
	db.demo.aggregate( [pipeline], <optional params> ) - performs an aggregation on a collection; returns a cursor
	db.demo.remove(query)
	db.demo.replaceOne( filter, replacement, <optional params> ) - replace the first matching document, optional parameters are: upsert, w, wtimeout, j
	db.demo.renameCollection( newName , <dropTarget> ) renames the collection.
	db.demo.runCommand( name , <options> ) runs a db command with the given name where the first param is the collection name
	db.demo.save(obj)
	db.demo.stats({scale: N, indexDetails: true/false, indexDetailsKey: <index key>, indexDetailsName: <index name>})
	db.demo.storageSize() - includes free space allocated to this collection
	db.demo.totalIndexSize() - size in bytes of all the indexes
	db.demo.totalSize() - storage allocated for all data and indexes
	db.demo.update( query, <update object or pipeline>[, upsert_bool, multi_bool] ) - instead of two flags, you can pass an object with fields: upsert, multi, hint
	db.demo.updateOne( filter, <update object or pipeline>, <optional params> ) - update the first matching document, optional parameters are: upsert, w, wtimeout, j, hint
	db.demo.updateMany( filter, <update object or pipeline>, <optional params> ) - update all matching documents, optional parameters are: upsert, w, wtimeout, j, hint
	db.demo.validate( <full> ) - SLOW
	db.demo.getShardVersion() - only for use with sharding
	db.demo.getShardDistribution() - prints statistics about data distribution in the cluster
	db.demo.getSplitKeysForChunks( <maxChunkSize> ) - calculates split points over all chunks and returns splitter function
	db.demo.getWriteConcern() - returns the write concern used for any operations on this collection, inherited from server/db if set
	db.demo.setWriteConcern( <write concern doc> ) - sets the write concern for writes to the collection
	db.demo.unsetWriteConcern( <write concern doc> ) - unsets the write concern for writes to the collection
	db.demo.latencyStats() - display operation latency histograms for this collection

> help keys
Tab completion and command history is available at the command prompt.
Some emacs keystrokes are available too:
  Ctrl-A start of line
  Ctrl-E end of line
  Ctrl-K del to end of line

Multi-line commands
You can enter a multi line javascript expression.  If parens, braces, etc. are not closed, you will see a new line 
beginning with '...' characters.  Type the rest of your expression.  Press Ctrl-C to abort the data entry if you
get stuck.

> db.HouseHold.find().help()
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({...})
	.maxTimeMS(<n>)
	.comment(<comment>)
	.tailable(<isAwaitData>)
	.noCursorTimeout()
	.allowPartialResults()
	.returnKey()
	.showRecordId() - adds a $recordId field to each returned object
	.allowDiskUse() - allow using disk in completing the query

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
	.pretty() - pretty print each document, possibly over multiple lines

use admin

db.createUser({
  user: 'admin',    // Óû§Ãû£¨×Ô¶¨Ò壩
  pwd: 'Abc123++',  // ÃÜÂ루×Ô¶¨Ò壩
  roles:[{
    role: 'root',   // ʹÓ󬼶Óû§½ÇÉ«
    db: 'admin'     // Ö¸¶¨Êý¾Ý¿â
  }]
})

# ²é¿´µ±Ç°¿âϵÄÓû§
show users
# ɾ³ýÓû§
db.dropUser('testadmin')
# ÐÞ¸ÄÓû§ÃÜÂë
db.updateUser('admin', {pwd: '654321'})
# ÃÜÂëÈÏÖ¤
db.auth('admin', '654321')

# ÐÂÔöÊý¾Ý
db.inventory.insertMany( [
    { item: "journal", qty: 25, size: { h: 14, w: 21, uom: "cm" }, status: "A" },
    { item: "notebook", qty: 50, size: { h: 8.5, w: 11, uom: "in" }, status: "A" },
    { item: "paper", qty: 100, size: { h: 8.5, w: 11, uom: "in" }, status: "D" },
    { item: "planner", qty: 75, size: { h: 22.85, w: 30, uom: "cm" }, status: "D" },
    { item: "postcard", qty: 45, size: { h: 10, w: 15.25, uom: "cm" }, status: "A" }
]);

# ǶÌ×Îĵµ²éѯ£¬size±ØÐëÍêÈ«Æ¥Åä
db.inventory.find( { size: { h: 14, w: 21, uom: "cm" } } )
# ǶÌ××ֶβéѯ£¬Ö±½Ó²éѯsize.uom¡£
db.inventory.find( { "size.uom": "in" } )

{ $dateToString: {
    date: <dateExpression>,
    format: <formatString>,
    timezone: <tzExpression>,
    onNull: <expression>
} }

db.getCollection('HouseHold').aggregate([
    {$project:
        {
            year:{$dateToString: { format: "%Y", date: "$createTime" }},
            dayofweek:{$dateToString: { format: "%w", date: "$createTime" }},
            weekofyear:{$dateToString: { format: "%U", date: "$createTime" }},
            year:{$dateToString: { format: "%Y-%m-%dT%H:%M", date: "$createTime" }},
            onNull:{$dateToString: { date: null, onNull: "No date supplied" } }
        }}
]).pretty()

{
    "_id" : ObjectId("60fa3b3635f8c5790b880297"),
    "year" : "2021",
    "dayofweek" : "5",
    "weekofyear" : "30",
    "UTC" : "2021-07-29T09:10",
    "onNull" : "No date supplied"
}

{
	"_id" : ObjectId("600631c7c8eb4369cf6ad9c8"),
	"name" : "»ñÈ¡",
	¡°³öÉú¡±£ºISODate£¨¡°2020-12-31T23£º30£º15.123Z¡±£©
}

db.pets.aggregate(
   [
     {
       $project: {
          timestamp: { $toDate: "$_id" },
          dateString: { $dateToString: { format: "%d-%m-%Y", date: "$_id" } }
       }
     }
   ]
).pretty()

{
	"_id" : ObjectId("600631c7c8eb4369cf6ad9c8"),
	"ʱ¼ä´Á" : ISODate("2021-01-19T01:11:35Z"),
	¡°ÈÕÆÚ×Ö·û´®¡±£º¡°19-01-2021¡±
}

{ $set: { <field1>: <value1>, ... } }
# Àý×Ó
db.col.update(
   { _id: 100 },
   { $set:
      {
        quantity: 500,
        details: { model: "14Q3", make: "xyz" },
        tags: [ "coats", "outerwear", "clothing" ]
      }
   }
)

# api
db.collection.remove(
   <query>,
   {
     justOne: <boolean>,
     writeConcern: <document>
   }
)

# Àý×Ó
db.col.remove({'title':'abc'})