Page 75 - CITS - Computer Software Application -TT
P. 75

COMPUTER SOFTWARE APPLICATION - CITS

















           Simplicity:  The  conceptual  ER  Model  construction  is  straightforward.  If  we  grasp  the  connections  between
           attributes and entities, developing the ER Diagram for the model becomes effortless.
           Efficient Communication Tool: Database designers extensively rely on this model to effectively convey their
           concepts.
           Smooth Transition to Various Models: This model harmonizes effectively with the relational model, seamlessly
           transforming the ER model into tables. Furthermore, it can be adapted into other models like the network model,
           hierarchical model, and more.
           Disadvantages of ER Model
           Lack of Notation  Consistency:  An  established  industry  standard  for  creating  an  ER  model  is  absent.
           Consequently, different developers might employ notations that are unclear to their peers.
           Concealed Information: The ER model’s high-level perspective can lead to the omission or concealment of
           certain details, potentially resulting in the loss of some information.
           Schema


           What is Schema?
           •  The  framework  of  the  database  takes  form  through  the
              attributes, and this framework is identified as the schema.
           •  A schema outlines the logical limitations, such as tables
              and primary keys, that define the structure of a database.

           •  The schema doesn’t encompass the data attribute types






































                                                           62

                              CITS : IT&ITES - Computer software application - Lesson 18 - 36
   70   71   72   73   74   75   76   77   78   79   80