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08_Relational Models (represents (the data in a database as a collection…
08_Relational Models
represents
the data in a database as a collection of relations
Table= rows, columns
query language
formal notation
relations
properties
domains
schema
database schema notation
instances
integrity constraints
check correctness of data in our relation
can operate at diff levels
single attribute
intra-relational contstraints
tuple constraint
key constraints
inter relational constraints
referential integrity constraints
foreign key
Keys
superkeys
minimum superkey
primary key
Definition data model in DBMS
a collection of concepts that can be used to describe the structure of a database
Representational data models
used to represent the data in a DBMS
they are
network
Relational
Hierarchical
Object-oriented
Physical data models
Conceptual data models