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① mongo命令行参数帮助
通过--help参数显示命令行帮助信息
mongo --help
显示:
MongoDB shell version: 2.0.4usage: mongo [options] [db address] [file names (ending in .js)]db address can be: foo foo database on local machine 192.169.0.5/foo foo database on 192.168.0.5 machine 192.169.0.5:9999/foo foo database on 192.168.0.5 machine on port 9999options: --shell run the shell after executing files --nodb don't connect to mongod on startup - no 'db address' arg expected --norc 开始不执行".mongorc.js"文件 --quiet 安静模式 --port arg 端口 --host arg IP --eval arg 运行javascript脚本 -u [ --username ] arg 用户名 -p [ --password ] arg 密码 -h [ --help ] 显示这个帮助信息 --version 版本号 --verbose increase verbosity --ipv6 开启IPv6支持(默认关闭)
② mongo指令帮助
通过命令提示符连上mongo数据库后,可以输入help来显示命令提示符帮助.
help
会显示:
db.help() 数据库方法帮助信息db.mycoll.help() 集合方法帮助信息rs.help() help on replica set methods
help admin 管理员帮助信息help connect 连接数据库帮助help keys 快捷键help misc 杂项信息帮助help mr mapreduce帮助show dbs 显示全部数据库名show collections 显示当前数据库中的全部集合名show users 显示当前数据库的全部用户show profile show most recent system.profile entries with time >= 1msshow logs 显示可以连接的日志(`logger`)名show log [name] 输出内存中的最近log的片段, 默认输出`global`use <db_name> 设定当前数据库db.foo.find() 显示集合`foo`中的对象列表db.foo.find( { a : 1 } ) 查询foo集合中`a == 1`的对象it 输入it, 继续迭代显示结果, 输出更多结果DBQuery.shellBatchSize = x 设置显示结果条数exit 退出命令行③ 数据库帮助
show dbs
db.help()
显示一个数据的方法的具体实现，输入db.<method name>不带(). 例如:
db.updateUser
显示:
test.updateUser
④ 集合帮助
show collections
db.collection.help()
显示
db.collection.find().help() - show DBCursor help
db.collection.count()db.collection.dataSize()db.collection.distinct( key ) - eg. db.collection.distinct( 'x' )db.collection.drop() drop the collection
db.collection.dropIndex(name)db.collection.dropIndexes()db.collection.ensureIndex(keypattern[,options]) - options is an object with these possible fields: name, unique, dropDups
db.collection.reIndex()db.collection.find([query],[fields]) - query is an optional query filter. fields is optional set of fields to return.
e.g. db.collection.find( {x:77} , {name:1, x:1} )db.collection.find(...).count()db.collection.find(...).limit(n)db.collection.find(...).skip(n)db.collection.find(...).sort(...)db.collection.findOne([query])db.collection.findAndModify( { update : ... , remove : bool [, query: {}, sort: {}, 'new': false] } )db.collection.getDB() get DB object associated with collection
db.collection.getIndexes()db.collection.group( { key : ..., initial: ..., reduce : ...[, cond: ...] } )db.collection.mapReduce( mapFunction , reduceFunction , <optional params> )db.collection.remove(query)db.collection.renameCollection( newName , <dropTarget> ) renames the collection.db.collection.runCommand( name , <options> ) runs a db command with the given name where the first param is the collection name
db.collection.save(obj)db.collection.stats()db.collection.storageSize() - includes free space allocated to this collection
db.collection.totalIndexSize() - size in bytes of all the indexes
db.collection.totalSize() - storage allocated for all data and indexes
db.collection.update(query, object[, upsert_bool, multi_bool])db.collection.validate( <full> ) - SLOW
db.collection.getShardVersion() - only for use with sharding
db.collection.getShardDistribution() - prints statistics about data distribution in the cluster显示方法实现输入db.<collection>.<method>, 不带(). 例如输入:
db.collection.save
显示:
function (obj) {
if (obj == null || typeof obj == "undefined") {
throw "can't save a null";
}
if (typeof obj == "number" || typeof obj == "string") {
throw "can't save a number or string";
}
if (typeof obj._id == "undefined") {
obj._id = new ObjectId;
return this.insert(obj);
} else {
return this.update({_id:obj._id}, obj, true);
}}⑤ cursor帮助
当你在mongo命令行使用find()方法时, 可以使用很多cursor方法来修改find()行为和结果.
显示find()方法可用的修改器和cursor处理方法
db.collection.find().help()
显示:
> db.collection.find().help()find() modifiers .sort( {...} )
.limit( n )
.skip( n )
.count() - total # of objects matching query, ignores skip,limit
.size() - total # of objects cursor would return, honors skip,limit
.explain([verbose])
.hint(...)
.showDiskLoc() - adds a $diskLoc field to each returned objectCursor methods .forEach( func )
.map( func )
.hasNext()
.next()看cursor方法的实现, 输入db.<collection>.find().<method>, 不包含(). 例如:
db.collection.find().toArray
显示:
> db.collection.find().toArrayfunction () {
if (this._arr) {
return this._arr;
}
var a = [];
while (this.hasNext()) {
a.push(this.next());
}
this._arr = a;
return a;}常用的cursor方法
hasNext() 查询cursor是否还有数据.
next() 返回下一个数据对象, 并且cursor指向位置加1.
forEach(
) 方法遍历执行全部结果. 只有1参数, 迭代器中指向的对象.
⑥ 包装对象帮助
可以通过输入help misc来获取对象包装类.
help misc
显示:
> help misc b = new BinData(subtype,base64str) create a BSON BinData value b.subtype() the BinData subtype (0..255) b.length() length of the BinData data in bytes b.hex() the data as a hex encoded string b.base64() the data as a base 64 encoded string b.toString() b = HexData(subtype,hexstr) create a BSON BinData value from a hex string b = UUID(hexstr) create a BSON BinData value of UUID subtype b = MD5(hexstr) create a BSON BinData value of MD5 subtype o = new ObjectId() create a new ObjectId o.getTimestamp() return timestamp derived from first 32 bits of the OID o.isObjectId() o.toString() o.equals(otherid)
⑦ 参考文章
官方文档
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