Amazon Software Development Engineer interview questions

I gave my resume at a job fair at purdue university and i got an email from amazon.com asking me to schedule for a phone interview. I set it up and I got the call which lasted for an hour, where they asked me several technical questions. 1 week later, i got an e-mail from them telling me since i lacked experience, they were rejecting me.

About 40~45 minutes phone interview. Very nice interviewer and didn't make me nervous at all. The interview started with some questions related to my experience like what kind of project I did and what's my duty and position in my current job. What's the most difficult things I've experienced and how did I solved it. After 10 minutes self intro, the interviews told me he wants to ask some technical questions. First he asked an SQL question. He gave me two tables(for ex, supermarket and items) and two columns in each table and asked me to read the query that calculates the prices of certain item. Second question is XML question. He gave me a simple xml file and asked me what's the most efficient way to get some data set. And then asked me if I can read a linux command for this.( My answer is to use xQuery 'cause I think this might be related to the previous question but he told me he's just asking me thought. So I'm not sure is it an algorithm question) Then he asked me to write a java program to print power set without using the ready-to-use power set class if there is. After that, he asked me to give a word to describe a good software and a word to describe good supervisor. (This might be my worst part.) He asked me to send my program back asap. I'm waiting for the second one on next week.