MongoDB的数据库基本操作（二）

创建数据库

>use mydb
switched to db mydb 

查看所有的数据表

>show collections
 system.indexes

创建数据表 

>db.createCollection("tb_user")
{"ok":1}

> db.createCollection("Test",{capped:true, size:10000}) { "ok" : 1 }

{"ok":1}

-- 说明

capped:true，表示该集合的结构不能被修改；

size:在建表之初就指定一定的空间大小，接下来 的插入操作会不断地按顺序APPEND数据在这个预分配好空间的文件中，如果已经超出空间大小，则回到文件头覆盖原来的数据继续插入。这种结构保证了插入 和查询的高效性，它不允许删除单个记录，更新的也有限制：不能超过原有记录的大小。这种表效率很高，它适用于一些暂时保存数据的场合，比如网站中登录用户 的session信息，又比如一些程序的监控日志，都是属于过了一定的时间就可以被覆盖的数据。

修改数据表名

 >db.tb_user.renameCollection("tb_user1")
{"ok":1}  

数据表帮助主题help

 > db.Account.help()

DBCollection help
        db.Account.find().help() - show DBCursor help
        db.Account.count()
        db.Account.dataSize()
        db.Account.distinct( key ) - eg. db.Account.distinct( 'x' )
        db.Account.drop() drop the collection
        db.Account.dropIndex(name)
        db.Account.dropIndexes()
        db.Account.ensureIndex(keypattern[,options]) - options is an object with these possible fields: name, unique, dropDups
        db.Account.reIndex()
        db.Account.find([query],[fields]) - query is an optional query filter. fields is optional set of fields to return.
                                                      e.g. db.Account.find( {x:77} , {name:1, x:1} )
        db.Account.find(...).count()
        db.Account.find(...).limit(n)
        db.Account.find(...).skip(n)
        db.Account.find(...).sort(...)
        db.Account.findOne([query])
        db.Account.findAndModify( { update : ... , remove : bool [, query: {}, sort: {}, 'new': false] } )
        db.Account.getDB() get DB object associated with collection
        db.Account.getIndexes()
        db.Account.group( { key : ..., initial: ..., reduce : ...[, cond: ...] } )
        db.Account.mapReduce( mapFunction , reduceFunction , <optional params> )
        db.Account.remove(query)
        db.Account.renameCollection( newName , <dropTarget> ) renames the collection.
        db.Account.runCommand( name , <options> ) runs a db command with the given name where the first param is the collection name
        db.Account.save(obj)
        db.Account.stats()
        db.Account.storageSize() - includes free space allocated to this collection
        db.Account.totalIndexSize() - size in bytes of all the indexes
        db.Account.totalSize() - storage allocated for all data and indexes
        db.Account.update(query, object[, upsert_bool, multi_bool])
        db.Account.validate() - SLOW
        db.Account.getShardVersion() - only for use with sharding

查询一条记录

> db.Account.findOne()
{
        "_id" : ObjectId("4ded95c3b7780a774a099b7c"),
        "UserName" : "libing",
        "Password" : "1",
        "Email" : "libing@126.cn",
        "RegisterDate" : "2011-06-07 11:06:25"
}

--SELECT TOP 1 * FROM Account

 

 查询聚集中字段的不同记录

> db.Account.distinct("UserName")

--SELECT DISTINCT("UserName")  FROM Account

 

 查询聚集中UserName包含“keyword”关键字的记录

db.Account.find({"UserName":/keyword/})

 --SELECT * FROM Account WHERE UserName LIKE '%keyword%'

 

查询聚集中UserName以"keyword" 开头的记录

> db.Account.find({"UserName":/^keyword/})

--SELECT * FROM Account WHERE UserName LIKE 'keyword%'

 

查询聚集中UserName以“keyword”结尾的记录

> db.Account.find({"UserName":/keyword$/})

--SELECT * FROM Account WHERE UserName LIKE '%keyword' 

 

查询聚集中指定列

> db.Account.find({},{"UserName":1,"Email":1})    --1:true

--SELECT UserName,Email FROM Account

 

 查询聚集中排除指定列

> db.Account.find({},{"UserName":0})    --0:false

 

查询聚集中指定列，且Age > 20

> db.Account.find({"Age":{"$gt":20}},{"UserName":1,"Email":1})

--SELECT UserName,Email FROM Account WHERE Age > 20 

 

聚集中字段排序 

> db.Account.find().sort({"UserName":1}) -- 升序
> db.Account.find().sort({"UserName":-1}) --降序

--SELECT * FROM Account ORDER BY UserName ASC

--SELECT * FROM Account ORDER BY UserName DESC 

 

统计聚集中记录条数

> db.Account.find().count()

--SELECT COUNT(*) FROM Account 

 

统计聚集中符合条件的记录条数

> db.Account.find({"Age":{"$gt":20}}).count()

-- SELECT COUNT(*) FROM Account WHERE Age > 20

 

统计聚集中字段符合条件的记录条数

> db.Account.find({"UserName":{"$exists":true}}).count()

--SELECT COUNT(UserName) FROM Account 

 

查询聚集中前5条记录 

> db.Account.find().limit(5)

--SELECT TOP 5 * FROM Account 

 

查询聚集中第10条以后的记录

> db.Account.find().skip(10)

--SELECT * FROM Account WHERE AccountID NOT IN (SELECT TOP 10 AccountID FROM Account) 

 

查询聚集中第10条记录以后的5条记录

> db.Account.find().skip(10).limit(5)

--SELECT TOP 5 * FROM Account WHERE AccountID NOT IN (SELECT TOP 10 AccountID FROM Account)

 

or查询

> db.Account.find({"$or":[{"UserName":/keyword/},{"Email":/keyword/}]},{"UserName":true,"Email":true})

--SELECT UserName,Email FROM Account WHERE UserName LIKE '%keyword%' OR Email LIKE '%keyword%' 

 

添加新记录

> db.Account.insert({AccountID:2,UserName:"lb",Password:"1",Age:25,Email:"libing@163.com",RegisterDate:"2011-06-09 16:36:95"})

修改记录

> db.Account.update({"AccountID":1},{"$set":{"Age":27,"Email":"libingql@163.com"}})
> db.Account.find({"AccountID":1})
{ "AccountID" : 1, "Age" : 27, "Email" : "libingql@163.com", "Password" : "1", "RegisterDate" : "2011-06-09 16:31:25", "UserName" : "libing", "_id" : ObjectId("4df08553188e444d001a763a") }

 

> db.Account.update({"AccountID":1},{"$inc":{"Age":1}})
> db.Account.find({"AccountID":1})
{ "AccountID" : 1, "Age" : 28, "Email" : "libingql@163.com", "Password" : "1", "RegisterDate" : "2011-06-09 16:31:25", "UserName" : "libing", "_id" : ObjectId("4df08553188e444d001a763a") }

 

删除记录

> db.Account.remove({"AccountID":1}) --DELETE FROM Account WHERE AccountID = 1

 

> db.Account.remove({"UserName":"libing"}) --DELETE FROM Account WHERE UserName = 'libing'

 

> db.Account.remove({"Age":{$lt:20}}) --DELETE FROM Account WHERE Age < 20
> db.Account.remove({"Age":{$lte:20}}) --DELETE FROM Account WHERE Age <= 20
> db.Account.remove({"Age":{$gt:20}}) --DELETE FROM Account WHERE Age > 20
> db.Account.remove({"Age":{$gte:20}}) --DELETE FROM Account WHERE Age >= 20
> db.Account.remove({"Age":{$ne:20}}) --DELETE FROM Account WHERE Age != 20

 

> db.Account.remove()    --全部删除
> db.Account.remove({})  --全部删除