physical and logical storage structures
Post on 01-Feb-2016
250 Views
Preview:
DESCRIPTION
TRANSCRIPT
PHYSICAL AND LOGICAL STORAGE STRUCTURES
LEVELS OF INTERFACE IN A DATABASE SYSTEM
LINKED LIST STRUCTURES
• A logical or sequential relationship of the records of a file is built into the file structure called linked list.
DIFFERENCE
EXAMPLE
KEYED – LIST STRUCTURE
• Its like an extension of linked list structure• For a different kind of classification an extra
record field is also added • Also called pointer fields – because it has no
direct relation with the record data in which it exists
• The pointer fields helps to order records in a logical fashion without having to use a computer programme
GRAPHICAL REPRESENTATION
HIERARCHICAL STRUCTURE• Data records arranged in different levels• To obtain data at a particular level , we have
first find the parent record
NETWORK STRUCTURE
• Used for complex network associations
top related