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Mr ZARKOVICInformation Systems and       Databases
Information Systems   This is the second core topic in the HSC    course i.e. it is compulsory   The syllabus begins wit...
DatabasesHowever, the major emphasis of this topic is on“… the process of organising, storing and retrieving data with da...
Skills for Information systems   For a given example of a database    information system students need to be    able to: ...
Examples of Information systems   To practice the above skills, the    syllabus suggests applying the    previous skills ...
Examples of Information systems   If it can be arranged, these systems can    be visited, with students noting down the  ...
Examples of Information systems   Alternatively, students may be asked    to research the RTA and the local    video shop...
Organisation Methods
Computer based vs Non-Computer            based   Students often get fixed on the idea that a    computer based solution ...
Computer based methods for         Organising Data   There are three choices    • Flat file systems    • Database Managem...
Flat File Systems   These systems store data in a single file   The data is divided up into columns (called    fields) a...
Flat File Systems   Key field – this field contains data to uniquely    identify every record in the database   These ar...
Database Management Systems              (DBMS)   A DBMS is the software used to    •   Create    •   Manage, and    •   ...
How a DBMS Works                      Database           D           B           M           SUser         Data Base      ...
Organisation of Relational               Databases   There are a number of files called tables    (sometimes called entit...
Design of relational databases   The purpose of the database will play    the major role in determining:    • How data wi...
Design of relational databases   An excellent example of how this is done    can be found at    http://hsc.csu.edu.au/ipt...
Design of relational databases   At this website there is also an    interesting and useful article that    describes the...
Design of relational databases   Page 30 of the syllabus support document    also has an example of a database    schemat...
Normalising a database   Getting a clear and unambiguous    definition of Database Normalisation    is very difficult   ...
Normalising a database   Powers => “Normalisation is the process    of organising data into tables so that the    results...
Normalising a database   Neither definition is very helpful   I define Normalisation as: “ the    process of organising ...
Storage and Retrieval
Data Independence   The database and the DBMS are two distinct    entities   As such each may be stored in separate loca...
Retrieving data from the database   The most common way of retrieving    information is using Query By Example   In Acce...
Structured Query Language (SQL)   SQL is a more powerful method of    retrieving data from a database   SQL queries are ...
Structured Query Language (SQL)   The four basic SQL statements are:    • SELECT - used to display data fields that      ...
Structured Query Language (SQL)   SELECT is used to display data fields    that satisfy a given rule    e.g. to search fo...
SQL – Wildcards   These are used when a complete value is    not known   ! is used to represent a single character   * ...
Joining Tables   SQL can be used to retrieve data from more than    one table, e.g.       SELECT Surname, City, PartName,...
Displaying Data   There are a number of ways to display    data in a database   We can view the individual data tables, ...
Social and Ethical Issues   There are many social and ethical issues to    consider with this topic   The most important...
THE END
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Info systems databases

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Info systems databases

  1. 1. Mr ZARKOVICInformation Systems and Databases
  2. 2. Information Systems This is the second core topic in the HSC course i.e. it is compulsory The syllabus begins with an overview of various types of information systems. Some of these systems form the basis of later option stands. For example: • Transaction processing systems • Decision support systems
  3. 3. DatabasesHowever, the major emphasis of this topic is on“… the process of organising, storing and retrieving data with database systems and hypermedia.”
  4. 4. Skills for Information systems For a given example of a database information system students need to be able to: • identify Participants • identify Data/information • identify Information technology • describe the relationship between participants, data/information and information technology
  5. 5. Examples of Information systems To practice the above skills, the syllabus suggests applying the previous skills to some example database systems: • School databases • RTA • Video store
  6. 6. Examples of Information systems If it can be arranged, these systems can be visited, with students noting down the participants, data/information, information technology and describing the various relationships An ‘excursion’ to the school library or to the administration section of the school is a cheap and easy (paper-work-wise) way to accomplish this goal
  7. 7. Examples of Information systems Alternatively, students may be asked to research the RTA and the local video shop in their own time Examples should not be limited to those given in the syllabus - you or the students may be able to come up with something localised or relevant to their experiences
  8. 8. Organisation Methods
  9. 9. Computer based vs Non-Computer based Students often get fixed on the idea that a computer based solution is always the most efficient and most appropriate The telephone book is an example of a non- computer based information system, that is efficient and sufficient for 99% of people for 99% of the time Compare the length of time it takes to look up a phone number in a book to the time taken to look up the same phone number on the internet Are there any advantages to using the internet for this task?
  10. 10. Computer based methods for Organising Data There are three choices • Flat file systems • Database Management Systems (to operate ‘relational’ databases) • Hypermedia The work on hypermedia is best held over until the next topic, Communication systems or the Multimedia option
  11. 11. Flat File Systems These systems store data in a single file The data is divided up into columns (called fields) and rows (called records) Data in fields are comprised of characters and form data of various types: alphanumeric (‘text’), numeric (including date, time, currency, etc), boolean (T/F, Y/N, M/F, etc) and so on Any of the simpler database programs – such as that found with Microsoft Works or AppleWorks create flat file databases
  12. 12. Flat File Systems Key field – this field contains data to uniquely identify every record in the database These are also used in relational databases Flat file databases are perfectly acceptable for certain situations They can become inefficient and difficult to manage for large volumes of data. Why? e.g. a student’s CD/DVD collection is a useful example to demonstrate ‘data redundancy’ in a flat-file database system
  13. 13. Database Management Systems (DBMS) A DBMS is the software used to • Create • Manage, and • Query… a database. A DBMS is used for more complex organisation of data, like that commonly used in a relational database It is not a part of the database - the database is just the collection of data files
  14. 14. How a DBMS Works Database D B M SUser Data Base Management System
  15. 15. Organisation of Relational Databases There are a number of files called tables (sometimes called entities or relations) The columns (fields) of each table are called attributes The rows (records) are known as tuples Each table must have a primary key Tables are linked by having a field in one table (foreign key) which is a primary key field in another table
  16. 16. Design of relational databases The purpose of the database will play the major role in determining: • How data will be organised in the database • How the database will be designed The process of designing a relational database is sometimes called ‘Database Modeling’
  17. 17. Design of relational databases An excellent example of how this is done can be found at http://hsc.csu.edu.au/ipt/info_systems/2-4/da Denise Tolhurst steps through the whole process from the design of the Entity Relationship Diagram (ERD) through to the construction of the database tables I have used this article with my IPT classes and used dummy data to create the database
  18. 18. Design of relational databases At this website there is also an interesting and useful article that describes the development of a database in terms of the system development cycle This later article has information on database schema, keys and data dictionaries
  19. 19. Design of relational databases Page 30 of the syllabus support document also has an example of a database schematic diagram Page 31-32 also has a great example of a relational database that could be used by a video store An interesting exercise is to get the class to work backward and develop the ERD for this database, then work forward and develop the schematic diagram and the database itself
  20. 20. Normalising a database Getting a clear and unambiguous definition of Database Normalisation is very difficult The ultimate goal of normalisation is simple: to reduce the amount of redundant data in a database How this is done is quite complex and barely within the ambit of the syllabus
  21. 21. Normalising a database Powers => “Normalisation is the process of organising data into tables so that the results of using the database are unambiguous and as intended” Ware, Cheleski & Chivers => “Normalising a relational database involves linking attributes directly from the original data fields and eliminating situations where attributes are linked to other attributes”
  22. 22. Normalising a database Neither definition is very helpful I define Normalisation as: “ the process of organising data into groups of tables in order to minimise data redundancy” NOTE: We can never completely eliminate redundant data
  23. 23. Storage and Retrieval
  24. 24. Data Independence The database and the DBMS are two distinct entities As such each may be stored in separate locations For example, the database itself may be stored on a database server. The software used to access the database may be Microsoft Access or FileMaker Pro that is stored on the user’s computer This allows for multiple users to have access the database simultaneously It also means that the DBMS may be updated without effecting the database
  25. 25. Retrieving data from the database The most common way of retrieving information is using Query By Example In Access this is done by • selecting the query button • selecting the fields you want to search and display • Entering a value for a field (criterion) • Pressing the query button This is a highly effective method for doing a search of data
  26. 26. Structured Query Language (SQL) SQL is a more powerful method of retrieving data from a database SQL queries are often embedded in other programming languages e.g. Cobol SQL is a programming language in itself however, for IPT we only need to know the basics
  27. 27. Structured Query Language (SQL) The four basic SQL statements are: • SELECT - used to display data fields that satisfy a given rule • UPDATE- change a value in a field/s • DELETE - delete a record from a file • INSERT – add a new record to the file
  28. 28. Structured Query Language (SQL) SELECT is used to display data fields that satisfy a given rule e.g. to search for the phone numbers and status of all suppliers in Paris we would use the following SELECT SupplierPhone, SupplierStatus FROM tblSupplier.tbl WHERE SupplierCity = “Paris”;
  29. 29. SQL – Wildcards These are used when a complete value is not known ! is used to represent a single character * is used to represent a group of characters e.g. SELECT SupplierName FROM tblSupplier.tbl WHERE SupplierCity = “*”; This would list all suppliers
  30. 30. Joining Tables SQL can be used to retrieve data from more than one table, e.g. SELECT Surname, City, PartName, Weight FROM tblSupplier, tblPart WHERE Supplier.City = “Paris” This query displays (selects) the fields Surname and City from the Supplier table and PartName and Weight from the Part table, on condition that the Supplier’s City is Paris
  31. 31. Displaying Data There are a number of ways to display data in a database We can view the individual data tables, where we can see all of the records that make up the table We can create forms to view individual records. We can even select which fields to display We can create a report that will display the data in a professional manner Reports can be made from queries
  32. 32. Social and Ethical Issues There are many social and ethical issues to consider with this topic The most important are Privacy, Security and Control and examples may include ‘identity theft’ and the cross-linking of previously independent government databases This has been discussed in earlier lectures Also see a provocative source of discussion at http://www.adcritic.com/interactive/view.php?%20id= Most of the existing texts do a good job covering these and other related issues
  33. 33. THE END

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