More Java interview questions

These are very basic questions but its good to review them

1. Explain Full Join, Right outer join, left outer join, with difference in them.
2. What will happen if I do a Right Outer join and there is no common data in second(left) table
Ans: all right table selected rows will be returns will left table selected data rows with null values.
3. What is outer and inner join.
4. difference in union and union all.
5. difference in truncate and delete.
6. if we have a table with a column named "Days" and this column have days data, count number of days for each type of day
Ans : select count(day) from table name group by day
7. What is inversion of control.
8. What is inversion of control by getter, setter and what is inversion of control by constructor.
9. difference in ibatis and hibernate(if you have worked on both).
10. how can you make a class immutable. (make class final, make methods final, and don't provide any setter for static or constant variables. )
11. What is abstract class, explain it.
12. Difference between hash table and hash map.