add a helper class to build raw sql statements and implement a function to provide select query with IDs
tested the function to generate select query with specified IDs
move default value of maximumOfIn to DeafultConfiguration
add an interface to represent a row of database tables
change the behavior when empty list is specified
update performance test
add some methods in Abstract DAO
[BUG_FIX] fix a bug that neglects to set code fragment mappings
implement queryRaw in CloneClassDao
make get(Collection) check whether the elements have already been retrieved