Fields are the values for each attribute. Fields may be fixed or variable length. Fixed length fields are normally used for data that is used for mathematical or other calculations, such as pixel values, where accuracy in data entry is important. Variable length fields are used or highly variable data such as descriptive data. Database data is normally access either by sequential or random access methods.
Sequential access is accomplished when data is arranged in contiguous, linear fashion.
An example of this method is tape storage. Sequential access is easy to program, however, it is generally slower than the random access method. Random access allows access to any data located on the storage device in a non-linear fashion. Database Management System. A DBMS has several consistent parts.