http://www.dotnetspider.com/resources/45972-Tricky-SQL-Server-Interview-Question-and-answers.aspx

delete from emp
where rowid not in
(select max(rowid) from emp group by empno);

SQL > delete from emp e1
where rowid not in
(select max(rowid) from emp e2
where e1.empno = e2.empno );

http://www.kendba.com/sample-chapters/oracle-sql-interview-questions/

http://techloverforum.blogspot.in/2014/02/51-oracle-sql-plsql-interview-questions.html

http://www.crazyforcode.com/break-string-dictionary-words/

http://searchdatascience.com/tag/java-heap-stack-variable-storage/
http://howtodoinjava.com/core-java/multi-threading/thread-synchronization-object-level-locking-and-class-level-locking/

http://howtodoinjava.com/core-java/multi-threading/thread-synchronization-object-level-locking-and-class-level-locking/

http://www.buggybread.com/2014/04/java-interview-questions-and-answers-on_5185.html

http://www.thejavageek.com/2013/07/21/initialization-blocks-constructors-and-their-order-of-execution/

http://chriswu.me/blog/a-lru-cache-in-10-lines-of-java/

https://dzone.com/articles/jvm-and-garbage-collection

http://jobcounter4all.blogspot.in/2013/06/java-virtual-machine-jvm-architecture.html

https://www.quora.com/Java-Virtual-Machine-JVM-Questions-on-java-native-memory

http://www.buggybread.com/2014/04/java-interview-questions-and-answers-on_706.html

https://www.cs.umd.edu/~pugh/java/memoryModel/jsr-133-faq.html

http://www.javabykiran.com/interview/corejava/jvm-management-interview-questions-1.php

http://www.programcreek.com/2013/09/string-is-passed-by-reference-in-java/
https://dzone.com/articles/hashmap-internal
http://javahungry.blogspot.com/2013/08/hashing-how-hash-map-works-in-java-or.html
http://javahungry.blogspot.com/2013/08/how-sets-are-implemented-internally-in.html

http://javahungry.blogspot.com/2015/04/difference-between-arraylist-and-linkedlist-in-java-example.html

Static methods and variables have been Stored in the PERMGEN space before the 8th version of the java. But,now they have introduced a new memory space called METASPACE now this is the place where all those name and fields of the class, methods of a class with the bytecode of the methods, constant pool, JIT optimizations  etc are stored.

    Reason for removing PERMGEN in java 8.0 is

           It is very hard to predict the required  size of PERMGEN..

           It helps in improving Garbage Collection Performance and Class data-de allocation..