DATA MODELS ::
an integrated collection of concept for describing data , relatinship b/w data & constraints(conditions & rules regulation) n an organizations …
Components of DM :
1. structural part :: rules & regulation which makes db
2.manipulation part ::define operation on data
3.integrity rules :: data validation
Types of DM ::
1. object Based DM : uses concepts such as entity, attr, relationships …..types r
entity relationship
semantic
functional
object oriented
2. record based DM : db consists of a num of fixed format records of possibly
different types
relational :: by table , name of column should be unique .. intersection of row & column
s cell
hireracharal :: tree str , link list
network ::data s represented as a collection of records. it's a circular list, so we don;t
have to waste time in searching because nodes r connected…
3.physical DM :: index mechanism , os + dbms work, how data s stord on HD, access
mechanism of data ….