Optimize the object mapping in GetDataList

- Optimize the object mapping in GetDataList
- Add the function name in Debug statements
Add debug statements to CreateSqlConnection

Add debug statements to CreateSqlConnection
Complete gSqlHelper and Map DBNull to null

- Complete gSqlHelper implementing all the public functions
- Map DBNull to null in GetDataList
- Make the appropriate tests in test GUI
Add Debug messages

- Add Debug Messages
- Optimize existing Debug Messages