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