Samsung Electronics Interview Question

SQL: write a code to join 3 tables ? what is outer and inner join ? what is the difference between left and right outer join ? machine learning: what is SVM ? how does it work ? what is cross validation ? data mining: How do you do document classification ? and they questioned a lot about the features stuff like td-idf ...etc what is a lexicon ...etc ? mind-twist: how many pendulums you can form between the numbers 1 to 10000 ?