1 CONCEPTUAL SCHEMA DESIGN PROCESS Information Processing and Technology, 2001 Yr 12 IPT

Information Processing and Technology Information Systems Database - a collection of (sorted) data Information Systems - is a database along with the means to effectively manipulate the information it contains e.g. libraries, video hire, employee records, student records, Microsoft Access.

Information Processing and Technology Database Views §internal view - the way data is stored onto a system §external view - the user’s view §conceptual view - the way the data relates *The conceptual view is independent of the system the database is implemented on.

Information Processing and Technology Universe of Discourse (UoD) The UoD is the domain of information being discussed by the client and database designer.

Information Processing and Technology Conceptual Schema Design Process The conceptual view is created by the Conceptual Schema Design Process (CSDP) NIAM (Nijssens Information Analysis Method) developed by GM Nijssen and ED Falkenberg l a process that links / structures information (UoD) by expressing facts and constraints graphically l also known as Object Role Modeling

Information Processing and Technology What does this data mean?

Information Processing and Technology Design Cycle 1.State elementary facts

Information Processing and Technology State Elementary Facts This step involves expressing information relevant to the UoD as elementary facts (EF). EF are simple unambiguous sentences that make statements about the UoD. EF are irreducible. They cannot be broken down into smaller parts and still convey the same information. EF do not use terms such as and, or, not, if, all, some or most. At this stage, or before, examples of information relevant to the database should be collected.

Information Processing and Technology The simplest type of elementary fact states that an object plays a role: Mary jogs This elementary fact states that an object (Mary) plays a role (jogs) 1. State Elementary Facts

Information Processing and Technology Which of these are elementary facts? §Leroy plays for the Bullets. §Mary does not smoke. §Ken and Jerry play hockey. §Jenny likes chocolate and ice-cream. §Jim flew to Sydney. §Alana flew to Melbourne and then to Sydney. §Mary ate Coco Pops for breakfast. §Everybody loves somebody sometime. §Rover begs. §I can never see what is in those 3d pictures. §Barry eats all berries. §Does Julie run?

Information Processing and Technology §Elementary sentences are composed of four key elements - 1. objects/entities 2. reference mode 3. roles 4. value or labels §The use of a reference scheme avoids ambiguity. Reference Scheme

Information Processing and Technology Reference Scheme §Object / entity types - are common groups that play roles Mary Studies English

Information Processing and Technology Roles - a role is a part played by an entity Mary studies English Reference Scheme

Information Processing and Technology §reference mode - the reference mode is a way of identifying an entity. Common reference modes are names, numbers, ID codes. They will be the fields in the database that you are creating. Student with first name Mary Reference Scheme

Information Processing and Technology §Values - a value or label gives a specific example of the entity. Student with the first name Mary studies Subject with the name IPT Reference Scheme role ref. mode Value / label entity

Information Processing and Technology Arity §The arity of an elementary sentence is the number of entities that associate or play roles

Information Processing and Technology Mary Jogs Arity - Unary 1 entity

Information Processing and Technology Mary studies English Arity - Binary 1 2

Information Processing and Technology Mary received a B for English Arity - Ternary 1 3 2

Information Processing and Technology Mary has English in Lesson 1 on Monday Arity - Quaternary And so on…

Information Processing and Technology Summary §The UoD is the domain of relevant information §An information system is designed through the Conceptual Schema Design Process (CSDP) §The first process of the CSDP is to state elementary facts. EF are simple, irreducible and do not contain and, if, or, not, all, some, most §EF contain entities, roles, reference modes and values / labels. §The number of entities in an EF describes its arity..