键值数据库了解mongoDB 博客分类： Database MongoDBJ#PythonjsonJavaScript

键值数据库了解mongoDB

首页
http://www.mongodb.org/display/DOCS/Home

mongo stand for a kind of fruit.haha.but the explain of the website is humongous.
humongous [hju:'mʌŋɡəs]  adj. 巨大无比的，极大的
mongo ['mɔŋɡəu] n 芒果

下载地址
http://www.mongodb.org/display/DOCS/Downloads

我下载了windows版本的来试试。得到文件：mongodb-win32-i386-1.2.3.zip

文档地址：
http://www.mongodb.org/display/DOCS/Tutorial

Getting the Database
start the mongod process:
C:\mongodb-win32-i386-1.2.3\bin\mongod.exe

报错如下：
Thu Feb 25 17:21:31 Assertion: dbpath (/data/db/) does not exist
Thu Feb 25 17:21:31   exception in initAndListen std::exception: dbpath (/data/db/) does not exist, terminating

新建文件夹d:\database\mongo\db\，然后运行：
mongod.exe -dbpath d:\database\mongo\db\

启动成功！

Getting A Database Connection
Start the MongoDB JavaScript shell with:
C:\mongodb-win32-i386-1.2.3\bin>mongo.exe
MongoDB shell version: 1.2.3
url: test
connecting to: test
type "exit" to exit
type "help" for help
>
选择数据库
use mydb

Inserting Data into A Collection
> j = {name:"mongo"};
{ "name" : "mongo" }
> t = {x : 3};
{ "x" : 3 }
> db.things.save(j);
> db.things.save(t);
> db.things.find();
{ "_id" : ObjectId("4b8765509a14000000003f6d"), "name" : "mongo" }
{ "_id" : ObjectId("4b87655c9a14000000003f6e"), "x" : 3 }

放入更多的元素
> for(var i = 1;i<10;i++) db.things.save({x:4,j:i})
> db.things.find();
{ "_id" : ObjectId("4b8765509a14000000003f6d"), "name" : "mongo" }
{ "_id" : ObjectId("4b87655c9a14000000003f6e"), "x" : 3 }
{ "_id" : ObjectId("4b8765d09a14000000003f6f"), "x" : 4, "j" : 1 }
{ "_id" : ObjectId("4b8765d09a14000000003f70"), "x" : 4, "j" : 2 }
{ "_id" : ObjectId("4b8765d09a14000000003f71"), "x" : 4, "j" : 3 }
{ "_id" : ObjectId("4b8765d09a14000000003f72"), "x" : 4, "j" : 4 }
{ "_id" : ObjectId("4b8765d09a14000000003f73"), "x" : 4, "j" : 5 }
{ "_id" : ObjectId("4b8765d09a14000000003f74"), "x" : 4, "j" : 6 }
{ "_id" : ObjectId("4b8765d09a14000000003f75"), "x" : 4, "j" : 7 }
{ "_id" : ObjectId("4b8765d09a14000000003f76"), "x" : 4, "j" : 8 }
{ "_id" : ObjectId("4b8765d09a14000000003f77"), "x" : 4, "j" : 9 }

Accessing Data From a Query
> var cursor = db.things.find();
> while (cursor.hasNext()){print(tojson(cursor.next()));}
{ "_id" : ObjectId("4b8765509a14000000003f6d"), "name" : "mongo" }
{ "_id" : ObjectId("4b87655c9a14000000003f6e"), "x" : 3 }
{ "_id" : ObjectId("4b8765d09a14000000003f6f"), "x" : 4, "j" : 1 }
{ "_id" : ObjectId("4b8765d09a14000000003f70"), "x" : 4, "j" : 2 }
{ "_id" : ObjectId("4b8765d09a14000000003f71"), "x" : 4, "j" : 3 }
{ "_id" : ObjectId("4b8765d09a14000000003f72"), "x" : 4, "j" : 4 }
{ "_id" : ObjectId("4b8765d09a14000000003f73"), "x" : 4, "j" : 5 }
{ "_id" : ObjectId("4b8765d09a14000000003f74"), "x" : 4, "j" : 6 }
{ "_id" : ObjectId("4b8765d09a14000000003f75"), "x" : 4, "j" : 7 }
{ "_id" : ObjectId("4b8765d09a14000000003f76"), "x" : 4, "j" : 8 }
{ "_id" : ObjectId("4b8765d09a14000000003f77"), "x" : 4, "j" : 9 }

The above example shows cursor-style iteration. The hasNext() function tells if there are any more documents to return, and the next() function returns the next document. We also used the built-in tojson() method to render the document in a pretty JSON-style format.

Repeating the example above, but using forEach() directly on the cursor rather than the while loop:
> db.things.find().forEach(function(x){ print(tojson(x));})
{ "_id" : ObjectId("4b8765509a14000000003f6d"), "name" : "mongo" }
{ "_id" : ObjectId("4b87655c9a14000000003f6e"), "x" : 3 }
{ "_id" : ObjectId("4b8765d09a14000000003f6f"), "x" : 4, "j" : 1 }
{ "_id" : ObjectId("4b8765d09a14000000003f70"), "x" : 4, "j" : 2 }
...

In the mongo shell, you can also treat cursors like an array :
> var cursor = db.things.find();
> print(tojson(cursor[4]));
{ "_id" : ObjectId("4b8765d09a14000000003f71"), "x" : 4, "j" : 3 }

Specifying What the Query Returns
SELECT * FROM things WHERE name="mongo"
> db.things.find({name:"mongo"}).forEach(function(x){print(tojson(x));});
{ "_id" : ObjectId("4b8765509a14000000003f6d"), "name" : "mongo" }

SELECT * FROM things WHERE x=4
> db.things.find({x:4}).forEach(function(x){print(tojson(x));});
{ "_id" : ObjectId("4b8765d09a14000000003f6f"), "x" : 4, "j" : 1 }
{ "_id" : ObjectId("4b8765d09a14000000003f70"), "x" : 4, "j" : 2 }
{ "_id" : ObjectId("4b8765d09a14000000003f71"), "x" : 4, "j" : 3 }
{ "_id" : ObjectId("4b8765d09a14000000003f72"), "x" : 4, "j" : 4 }
...
A query document of the form { a:A, b:B, ... } means "where a==A and b==B and ...".

MongoDB also lets you return "partial documents" - documents that have only a subset of the elements of the document stored in the database.
SELECT j FROM things WHERE x=4
> db.things.find({x:4},{j:true}).forEach(function(x){print(tojson(x));});
{ "_id" : ObjectId("4b8765d09a14000000003f6f"), "j" : 1 }
{ "_id" : ObjectId("4b8765d09a14000000003f70"), "j" : 2 }
{ "_id" : ObjectId("4b8765d09a14000000003f71"), "j" : 3 }
{ "_id" : ObjectId("4b8765d09a14000000003f72"), "j" : 4 }
...

findOne()
> var mongo = db.things.findOne({name:"mongo"});
> print(tojson(mongo))
{ "_id" : ObjectId("4b8765509a14000000003f6d"), "name" : "mongo" }

> var mongo = db.things.findOne({x : 4});
> print(tojson(mongo))
{ "_id" : ObjectId("4b8765d09a14000000003f6f"), "x" : 4, "j" : 1 }

Limiting the Result Set via limit()
> db.things.find().limit(3);
{ "_id" : ObjectId("4b8765509a14000000003f6d"), "name" : "mongo" }
{ "_id" : ObjectId("4b87655c9a14000000003f6e"), "x" : 3 }
{ "_id" : ObjectId("4b8765d09a14000000003f6f"), "x" : 4, "j" : 1 }

进一步学习文档
http://www.mongodb.org/display/DOCS/Manual

各种驱动下载地址
http://www.mongodb.org/display/DOCS/Drivers
我主要了解JAVA和python两种语言如何去操作这个数据库。嘿嘿。
java驱动地址
http://www.mongodb.org/display/DOCS/Java+Language+Center
python驱动地址
http://api.mongodb.org/python/1.4%2B/index.html

最先看看java的吧，下载得到文件：mongo-1.2.jar，引入到classpath，参考文档如下：
http://www.mongodb.org/display/DOCS/Java+Tutorial

参考官方文档，写了个简单的示例程序，看到别人的BLOG立面，还可以支持implements DBObject，我没有测试成功。不知道是不是版本问题。
package com.easymessage;

import java.net.UnknownHostException;
import java.util.Set;

import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.Mongo;
import com.mongodb.MongoException;

public class MainTest {

public static void main(String[] args) {
// connect to the database
Mongo m = null;
try {
m = new Mongo("localhost", 27017);
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (MongoException e) {
e.printStackTrace();
}

DB db = m.getDB("mydb");

// authenticate
boolean auth = db.authenticate("username", "pwd".toCharArray());
System.out.println(auth);

// show all the collections
Set<String> colls = db.getCollectionNames();
for (String s : colls) {
System.out.println(s);
}

// get a collection
DBCollection coll = db.getCollection("test");

// insert some data
BasicDBObject user = new BasicDBObject();
user.put("name", "sillycat");
user.put("age", 28);
BasicDBObject address = new BasicDBObject();
address.put("place", "Chengdu");
address.put("code", 641000);
user.put("address", address);
coll.insert(user);

// find one data
DBObject myuser = coll.findOne();
System.out.println(myuser);

// insert data
for (int i = 0; i < 100; i++) {
coll.insert(new BasicDBObject().append("i", i));
}
// show the datacount
System.out.println(coll.getCount());

// use DBCursor
DBCursor cur = coll.find();
while (cur.hasNext()) {
cur.next();
// System.out.println(cur.next());
}

// select * from test where i = 71
BasicDBObject query = new BasicDBObject();
query.put("i", 71);
cur = coll.find(query);
while (cur.hasNext()) {
DBObject ob = cur.next();
System.out.println("kill========" + ob);
// remove one data
coll.remove(ob);
}

query = new BasicDBObject();
query.put("i", 71);
cur = coll.find(query);
System.out.println("left==========" + cur.count());

// select * from test where i > 99
query = new BasicDBObject();
query.put("i", new BasicDBObject("$gt", 98));
cur = coll.find(query);
while (cur.hasNext()) {
System.out.println(cur.next());
}

// select * from test where 51<i<52
query = new BasicDBObject();
query.put("i", new BasicDBObject("$gt", 51).append("$lte", 52));
cur = coll.find(query);
while (cur.hasNext()) {
System.out.println(cur.next());
}

// get a name list of the database
for (String s : m.getDatabaseNames()) {
System.out.println(s);
}

// get a database
DB temp_db = m.getDB("mydb");
System.out.println(temp_db.getName());

// drop a database by name
m.dropDatabase("mydb");

}

}