MongoDB rename a database

As of now, there is not a straight forward way to rename a MongoDB database. But you can use the following steps to achieve so :

Here, we are trying to rename OLD_DB to NEW_DB

Steps :
1) copy old database to new one using db.CopyDatabase( OLD_DB, NEW_DB )
2) switching to OLD_DB and dropping the database

Mongo Command :

  #Step 1 : Copy database to new name

  #Step 2 and 3, drop OLD_DB
     use OLD_DB

MongoDB Drop Database

We can use the following query to drop ( DELETE EVERYTHING) from a MongoDB database

( please be careful on running the query, it deletes everything )

   use [database]

MongoDB Like Query

We can do the following to achieve SQL's LIKE equivalent on a Query :

MongoDB :  db.users.find({"name": /jo/})

MYSQL Equivalent:   select * from users where name like '%jo%' 

MongoDB - show all database in server

We can use following commands to view all databases in the server
   show dbs
   show databases

MongoDB - List all collection from selected DB

There are two ways to do so, so far :

1 ) using  reference variable 'db'

2) using show command
    show collections

MongoDB : use database / switch to different database

MongoDB uses same syntax as SQL/MySQL to switch to different database :

MongoDB Syntax :
SQL Syntax :
     use DATABASE_NAME ;

Speech Recognition using HMM and VQ - Code Updates

Hey guys,

I've done some minor changes to the Speech Recognition code that I pushed to github/googlecode couple of years ago. As I received several attention/queries from readers/students all over the world regarding couple of minor bugs within the project, I thought its time ( better late than never :P ) to address them into the code.

Significant changes are on:

- Exception handling
- File handling
- File (recorded WAVE file, VQ codebook, HMM models) save path corrected
- Delta calculation fixed when regression window is less than number of frames ( when a short audio sample is recorded)

I've also uploaded training audio samples for few  words, trained Vector Quantization coebook and trained HMM model file for the words.

If you wish to add/train more words, please use the GUI - "HMM_VQ_Speech_Recognition" class. Just a note, you need to re-train both VQ and HMM for each word that you add.

Code :

Report File (contains both Speech and Speaker recognition)

I hope everyone will benefit from this. Keep coding, keep learning. Please let me know if you see any issues.

Thank you!

Ynaxdh - answer acronym in Yeoman generator

Meaning of Ynaxdh in Yeoman generator

Here the complete list of options/meanings:

  • Y: yes (Default)
  • n: no
  • a: always yes (yes to this question and all others)
  • x: exit
  • d: show the differences between the old and the new file
  • h: help, list all options

Notes :   

  • If you don't remember this definitions you can always enter h and see the list.
  • Also in the new version, when you enter one of the letters you will see the definition showing behind the question so that you can verify your answer before pressing Enter key.
  • The one in uppercase is the default one. If that is your choice, you can just hit enter.

QC/QA/Software Testing Training Videos Free

I've listed some useful videos that would be beneficial for  beginners or some one who wants to understand software testing from scratch. These are free and best  videos that I found on YouTube.

You can watch these in sequence. The first three videos discusses the fundamental and the 4th and 5th playlist has the information in depth.

1) Open Lecture by James Bach on Software Testing


3) Software Testing Tutorial for beginners

4) Manual Testing Tutorials: 34+ videos


5)Software Testing Videos: 9+ videos

Java Tutorials - Kindle epub/mobi format

Learning the java language can be tough if you follow wrong documents. It's always best to follow the official tutorials provided by Oracle. They have provided all the Java Tutorials which are present on its website in ePub and mobi format.

You can download all of them at

Check for the latest version of above page. Currently the link contains docs for Java8. It will prompt you the link for new version once later versions are released.