Required files
      
      extlib  
      data_objects/version  
      data_objects/logger  
      data_objects/connection  
      data_objects/uri  
      data_objects/transaction  
      data_objects/command  
      data_objects/result  
      data_objects/reader  
      data_objects/quoting  
      data_objects/error  
      data_objects/error/sql_error  
      data_objects/error/connection_error  
      data_objects/error/data_error  
      data_objects/error/integrity_error  
      data_objects/error/syntax_error  
      data_objects/error/transaction_error