[一般DB]		[MongoDB]
Database	->	Database
Table	->	Collection
Row	->	Document

(1) Create Database and a Collection 

> use <databaseName>

> db.createCollection (<name>)

E.g.: Create a Database named "myDatabase" and a Collection named "score"

> use myDatabase

> db.createCollection(score);

(2) Insert (Save) a record

> db.collectionName.save(<JSON document>);

E.g.: Save a document with name = Johnny, age=20, score=100

> db.score.save({"name":"Johnny","age":20,"score":100});

> db.score.save({"name":"William","age":25,"score":90,});

> db.score.save({"name":"Eric","age":30,"score":85,"language":["English","Chinese"]});

(3) Query record(s)

> db.score.find({key:value}>);

E.g.: Find documents that contain name == Johnny in "score" collection

> db.score.find({"name":"Johnny"});

(4) Update a record / row

> db.collectionName.update(<condition>,<the new fields({key:value,...})>);

E.g.: Update document with "name":"Johnny" to "name":"Ricky"

> db.score.update({"name":"Johnny"},{"name":"Ricky"});

Notes: This update will only replace the first document that matches to the <condition> and also all of the fields in the matching document will be replaced by <the new fields({key:value,...})>;

Modifier Operations: 

- $set 用來 update 某個 document 但是只針對某個 field 做 update. 

E.g.: 將 name == William 的document更新其 score 成 100 

> db.score.update({"name":"William"},{$set:{"score":100}});

- $push 用來增加一個元素(element)到 Document 的 某個欄位的 array 裡

E.g.: 將 Eric 的 language array 加一個 "Taiwanese"

> db.score.update({"name":"Eric"},{$push:{"language":"Taiwanese"}});

- $pop 用來移除(removes) document 中的array第一個元素或最後一個元素

E.g.: 將 Eric 的 language array 中的最後一個元素移除

> db.score.update({"name":"Eric"},{$pop:{"language":1}});

E.g.: 將 Eric 的 language array 中的第一個元素移除

> db.score.update({"name":"Eric"},{$pop:{"language":-1}});

- $pull 用來移除所有符合 key:value 的 array元素

E.g.: 將 Eric 的 language array 中符合 language == English 的移除

> db.score.update({"name":"Eric"},"{$pull:{"language":"English"}}");