WIH3002_Lecture slides_Sem2_Week 2_2024_v2_Abbr.pdf

Information Systems III (WIH3001) Advanced Design Data and Process Modeling Dr Bukelwa Ngoqo E-mail : [email protected] Office number : R253 Learning Objectives (1 of 2) DFD (Practice uestions.) Draw context diagrams Create a da...

Information Systems III (WIH3001) Advanced Design Data and Process Modeling Dr Bukelwa Ngoqo E-mail : [email protected] Office number : R253 Learning Objectives (1 of 2) DFD (Practice uestions.) Draw context diagrams Create a data dictionary DFD - Questions 1. Using the example of a retail clothing store in a mall, list relevant data flows, data stores, processes, and sources/sinks. Observe several sales transactions. Draw a context diagram and a level-0 diagram that represent the selling system at the store. Explain why you chose certain elements as processes versus sources/sinks. DFD - Questions 2. Using the example of Gautrain Passenger Train ticketing system, list relevant data flows, data stores, processes, and sources/sinks. Observe several sales transactions. Draw a context diagram and a level-1 DFD diagram that represent the ticket sales system. Explain why you chose certain elements as processes versus sources/sinks. DFD – Recap (Levels)  DFDs can range from simple overviews to complex, granular representations of a system or process with multiple levels, starting with level 0.  The most common and intuitive DFDs are level 0 DFDs, also called context diagrams. They’re digestible, high-level overviews of the flow of information through a system or process, so almost anyone can understand it. Level 0: Context Diagram  This DFD level focuses on high-level system processes or functions and the data sources that flow to or from them. Level 0 diagrams are designed to be simple, straightforward overviews of a process or system. DFD – Recap (Levels) Level 1: Process Decomposition  While level 1 DFDs are still broad overviews of a system or process, they’re also more detailed — they break down the system’s single process node into subprocesses. Level 2: Deeper Dives  The next level of DFDs dives even deeper into detail by breaking down each level 1 process into granular subprocesses. Level 3: Increasing Complexity  Level 3 and higher-numbered DFDs are uncommon. This is largely due to the amount of detail required, which defeats its original purpose of being easy to understand. Context Diagrams  A context class diagram is an information system development tool used by software developers to represent the relationship between the main product and its various subsystems or components.  A context diagram outlines how external entities interact with an internal software system.  It’s the most basic form of a data flow diagram, providing a broad view of the system and external entities in an easily digestible way.  Because of its simplicity, it’s sometimes called a level 0 data flow diagram.  A system context diagram is typically drawn with the system in the middle (either in a circle or a square). Context Diagrams  Also known as a Level 0 Data Flow Diagram (DFD), provides a high-level view of an information system and does not go into details about processes.  Context diagrams are typically included in requirements documents to show how the system interacts and will interface with other systems. Example Context Diagram – Example 1 Example Context Diagram – Example 2 Data Dictionary Data Dictionary (Uses)  Central storehouse of information about a system’s data An analyst uses the data dictionary to collect, document, and organize specific facts about a system Defines and describes all data elements and meaningful combinations of data elements Data Dictionary (Constructs)  Data element (i.e., data item or field) Smallest piece of data that has meaning within an information system Combined into records (i.e., data structures) - Record: meaningful combination of related data elements that is included in a data flow or retained in a data store Data Dictionary (Tools)  Using CASE tools for documentation More complex the system, more difficult it is to maintain full and accurate documentation Modern CASE tools simplify the task A CASE repository ensures data consistency Data Dictionary (Documenting)  Documenting the data elements Every data element in the data dictionary should be documented Objective: provide clear, comprehensive information about the data and processes that make up a system Data Dictionary (Contents) - Description  Recorded and described attributes Data element name and label Alias Type and length Default value Acceptable values Source Security Responsible user(s) Description and comments Data Dictionary (Contents) – Data Flows  Documenting the data flows Data flow name or label Description Alternate name(s) Origin Destination Record Volume and frequency Data Dictionary (Contents) – Data Stores  Documenting the data stores Data store name or label Description Alternate name(s) Attributes Volume and frequency Data Dictionary (Contents) - Process  Documenting the processes Process name or label Description Process number Process description Data Dictionary (Contents) - Entities  Documenting the entities Entity name Description Alternate name(s) Input data flows Output data flows Data Dictionary (Contents) - Records  Documenting the records Record or data structure name Definition or description Alternate name(s) Attributes Data Dictionary (Reports)  Data dictionary reports Alphabetized list of all data elements Report describing each data element and indicating the user or department Report of all data flows and data stores that use a particular data element Detailed reports showing all characteristics of data elements, records, data flows, processes, or any other selected item stored in the data Activity 1 – Create DB  DB Name: WIH3002DB  Create the following table: Persons Artist First Name Last Name Address City ID Activity 1 – Create DB  DB Name: WIH3002DB  Create the following table: MusicCatalogue Barcod Song Album Year Artist ID e SQL – Table(s) CREATE TABLEtable_name( column1 datatype, column2 datatype, column3 datatype,.... ); Answer 1: Create Database WIH3002DB; CREATE TABLE Persons ( ArtistID int, LastName varchar(255), FirstName varchar(255), ResAddress varchar(255), City varchar(255) ); Answer 1: Use Database WIH3002DB; CREATE TABLE MusicCatalogue ( ArtistID int, Barcode varchar(255), Song varchar(255), Album varchar(255), Year date ); Activity 2 – Insert Values  Insert into Table: Persons Artist First Name Last Name Address City ID 1 Sam Smith 12 Lovesong New York Lane 2 Whitney Houston 100 RandB Bloemfontein Street Answer 2: INSERT INTO WIH3002DB.dbo.Persons (ArtistID,LastName,FirstName,ResAddress,City) VALUES ( 1,'Smith','Sam','12 Lovesong Lane','New York'), ( 2,'Houston','Whitney','100 RandB Street','Bloemfontein') ; Activity 1 – Create DB  Insert into table: MusicCatalogue Barcod Song Album Year Artist ID e 0000450 Too good at The thrill of it All 2017 1 goodbyes 0000451 I have Whitney 1987 2 nothing 0000459 Where you Whitney 1987 2 are 0000600 I have The Bodyguard 1992 2 nothing Answer 2: INSERT INTO WIH3002DB.dbo.MusicCatalogue (Barcode,Song,Album,Year,ArtistId) VALUES ('0000450', 'Too good at goodbyes','The thrill of it All', '2017',1), ('0000451', 'I have nothing','Whitney', '1987', 2), ('0000459', 'Where you are','Whitney', '1987', 2), ('0000600', 'I have nothing','The Bodyguard','1987', 2) ; Activity 3 - Query  Select(display) from the database the name of the artist (and the name of the song(s)) who released a song(s) in 1987. Any Qs?