The aim of this refactoring is to improve and restructure the implementation of SQLStatementStore. The step proposed for refactoring are:
1) Moving the SQLFieldInfo fields= _engine.getInfo() to the constructor and make it a class attribute because it is being used by different methods.
2) Moving SQLColumnInfo ids = _engine.getColumnInfoForIdentities() to the constructor and make it a class attribute because it is being used by different methods.
3) Separates the PrepareStatement from execute statement. Construct a new method that only deals with preparing statement and then call this method from within executestatement. This way the code should be more structured and modular as well.
4) Moving Identity size check from SQLStatementStore to SQLEngine.
5) Move the Storage of extended classes to the ClassMolder