Why is a Java program platform independent? What are the features of Java? Which component makes it platform independent?

What does constraints in SQL mean? Which are the different types of Integrity Constraints? What happens if a constraint is violated?

What is a Java applet and a Java application? What are the differences between the two? What are the advantages of an applet over a Java application?

Why do the Android app developers use the Java language for creating apps? Why not any other language? What makes suing Java very important?

I am working on a windows application in my organization. We are going to implement this application now on web as well as on mobile also. Can someone suggest what should be the correct approach for that and also it should not be too costly? We are willing to use RESTful services for this implementation. Currently application is on Microsoft framework 3.5 and sql server as backend. Can someone please elaborate more on RESTful services?

I need some information on PDB. I am working on Microsoft Framework 2.0 and I need to implement pbd in it. I am not able to debug my release without it. I have compiled my code and tried generating the pdb file, but the system is throwing an error while generating pdb. Also I am doubtful that if I include this file, my applications run time will increase and its performance will hence decrease. Please throw some light on this.

I am developing a website with Ruby on Rails and facing some problems with API. I am creating a playlist based on user’s interest, where user can interact with it. I have heard of the usage of RSpotify that it can solve problems related to playlist. Can somebody explain usage of RSpotify with some basic and simple example? I know that it renders data in JSON format, but not properly aware of how is it helpful in my case. Also please explain how it validates a user’s account.

 I am facing some issues while implementing airspace solutions in WPF. Child and parent windows are not getting clipped and rendered. I have tried learning on clipping behavior of Windows 32 and found that the child windows are totally handled by another thread, which is causing this problem and one can solve this by enforcing WS_CLIPSIBLINGS, but I am not able to implement the same. How can I use WPF to solve this issue efficiently?

I am finding a way to reliably restart only mysql service in Ubuntu without harming rest of the processes. I am failing to do so as my command: sudo /etc/init.d/mysql stop makes not only the terminal to hang but also entire CPU gets struct. The CPU usage shoots to almost 100% and nothing happens thereafter until i forcefully close the application entirely. AM i trying to close the mysql service in a wrong way? Can anybody help me on this restarting issue? Any comments are highly appreciated

I am looking for your kind help in joining multiple columns from different tables into one table.