Presentation on theme: "UNIT 16 DATABASE SYSTEMS Lynda Spencelayh1 11. P1 -Principles of a Database System zExplain the principles of a database system, consider the advantages."— Presentation transcript:
P1 -Principles of a Database System zExplain the principles of a database system, consider the advantages & disadvantages of using databases. zEnsure you identify at least two advantages and two disadvantages- base these on your case study. Lynda Spencelayh2
Principles of database systems zGive examples can include - how the database system you have created supports the college / tutor. zInclude benefits using database tools [queries, forms, reports & macros - such as buttons] Lynda Spencelayh3
4 4 4 Principles of database systems zDatabases are everywhere colleges, dentists, supermarkets, banks, DVD stores, hospitals, hotels, gyms, - there are many more examples. zWithin each of these organisations the following information could be store; customers, sales, products, suppliers, purchasers, Stock, accounts, VAT.
Lynda Spencelayh5 5 5 zThese databases are organised in such a way that data can be easily entered, stored, edited, deleted and manipulated to support the activities of the organisation.
Lynda Spencelayh6 6 6 Advantages zEasy to use zrecords are easy to access and retrieve zdata can easily be manipulated in many ways zdata can be validated to ensure that it is accurate when input zeasy to store
Lynda Spencelayh7 7 7 Disadvantages zDatabase structures must be carefully developed to ensure that they work as efficiently as possible zthere are laws that control the use of databases zmany people feel that simply too much information is stored about us zthe cost of technology can be prohibitive
Lynda Spencelayh8 Data Types Just as with software development understanding data types is an important part of being able to work successfully with databases. zText - allows you to hold alphanumeric data. Means can hold numbers and characters, combinations give examples mention the default numbers that are set and the numbers that can be adjusted to. zNumber- whole numbers, decimals ect
Lynda Spencelayh9 Data Types zCurrency- As with number need to choose correct settings zDate/Time- Recognizes formats give examples short medium dates zAutoNumber- a number the computer automatically generates. Example what it does? zLookupWizard- able to set up values that are stored in advance user can make a choice from a list - give examples
Lynda Spencelayh10Lynda Spencelayh10Lynda Spencelayh10 Terminology zAn object is something that can be designed, selected and manipulated Tables, queries, forms and reports are all examples of objects. zTables consists of rows and columns, where the row contains a record and the column becomes a record field.
Lynda Spencelayh11 Database Structures zTables are the foundation to a database - Most databases contain number of tables they store different information. Give examples of information. zFields are the columns in the table. Each column has a field heading basically a name give example.. All the data in the field will be of the same type example…. And related give examples….
Lynda Spencelayh12 Database Structures zRecord - a record is a single piece of information with all the relevant parts give an example of a complete single record. zEach record is stored in a row.
Lynda Spencelayh13 Database Structures zPrimary Key - Each record that is stored must have something completely unique about it. This is so the records that are similar can be told apart. zUsually a field is selected which will contain a unique piece of data. zThis is then allocated a primary key give examples of unsuitable and suitable field names with simple reasons why zID is created, often using the Auto Number give reasons why?
Lynda Spencelayh14 Forms zTo enable users to use databases more easily, the data in tables is often [in fact usually] accessed through a form zthe form changes the way the user accesses and uses the records.
Lynda Spencelayh15Lynda Spencelayh15Lynda Spencelayh15 Query structure zUsed to interrogate the data in a database. This means filtering and sorting the data to answer questions. zThe query uses the data in the table, by searching the information in the fields and applying the chosen criteria.
Lynda Spencelayh16Lynda Spencelayh16Lynda Spencelayh16 Sorting records zYou can sort data via the query in design view. zYou can also sort data directly in the table. zSimply click on the relevant field and one of the sorting icons. A to[ascending order] or Z to A [descending order]
Lynda Spencelayh17Lynda Spencelayh17Lynda Spencelayh17 Reports zA report is a printed record of data in the database. zThere are several benefits of presenting information in a report rather than just viewing the data on-screen.
Lynda Spencelayh18Lynda Spencelayh18 Layouts zColumnar layout- each record is laid out with the fields underneath each other. The labels are placed to the left of the data. This layout ideal when there is a lot of data in each record. zTabular layout - this arranges the data in a table can be used for forms and reports if the amount of data in each record fits comfortably. zJustified layout- this displays data one record at a time. The appearance is a formal boxed style. Which fits neatly across the page, with the labels for each field above the data. It makes efficient use of space.
Lynda Spencelayh19Lynda Spencelayh19 D1 - Reports zIt counts the records in the report and displays the result. zit adds a heading that can be changed by the user. zIt adds the date and time. zIt adds a age number
Lynda Spencelayh20Lynda Spencelayh20 Reports – D2 zReports are very useful if you wish to share some of the information in the database with others in a printed format. zReports can be laid out so they are easy to read and understand zReports can be used to select and present exactly the data that someone needs rather than everything in the database. zAlthough reports are intended to be printed as hard copy, they can also be transferred as electronic documents by email.