Introduction to Database Development
اسلاید 1: COMU114: Introduction to Database Development1. Databases and Database Design
اسلاید 2: Teaching staffJim Paterson Room M628 James.Paterson@gcal.ac.uk COMU114 Introduction to Database Development 1. Databases and Database Design#2
اسلاید 3: Online resourcesBlackboardAnnouncementsAssessment informationwww.paterson.co.uk/gcal/intro2db.htmlLecture notes, lab & tutorial sheets, etcLinks to other resources COMU114 Introduction to Database Development 1. Databases and Database Design#3
اسلاید 4: ReadingNo set text – notes will be providedThe following books may be useful additional reading:Beginning Database Design: From Novice to Professional (Clare Churcher, Apress, ISBN 1-59059-769-9)Head First SQL (Lynn Beighley, OReilly, ISBN 0-596-52684-9)Many other books on databases and SQL in the library COMU114 Introduction to Database Development 1. Databases and Database Design#4
اسلاید 5: What is a database?Any collection of data can be described as a database Computerised database systems are now very commonplaceInformation is stored in a database every time we: use a bank accountbook a travel ticketmake an appointment with a doctoretc. COMU114 Introduction to Database Development 1. Databases and Database Design#5
اسلاید 6: Database mangement systemsA database is simply the collection of data which you need to storeTo actually store the data, and to do anything useful with it, you need a Database Management System (DBMS)A DBMS controls the way the data is stored on the computer, and provides ways of getting data in and out of the system COMU114 Introduction to Database Development 1. Databases and Database Design#6
اسلاید 7: Data modelsThe way in which data is organised for storage in a database is known as the data model Early computer databases developed in the 1960’s used a hierarchical modelSimilar to the way files and folders are still organised in modern computer file systemsMost data does not fit very well into a simple hierarchy COMU114 Introduction to Database Development 1. Databases and Database Design#7
اسلاید 8: Data modelsHierarchical data“Real-world” data – no clear hierarchy COMU114 Introduction to Database Development 1. Databases and Database Design#8
اسلاید 9: Relational databasesComplex data like this is better handled with the relational modelDevised by Edgar Codd around 1970Most databases nowadays are relational databasesalthough there are others: object databases, XML databasesA database management system which uses the relational model is called an RDBMS COMU114 Introduction to Database Development 1. Databases and Database Design#9
اسلاید 10: Databases and Enterprise Information Systems COMU114 Introduction to Database Development 1. Databases and Database Design#10
اسلاید 11: Simpler architectureCommonly used for smaller systemsDoesn’t scale wellCan be harder to maintain COMU114 Introduction to Database Development 1. Databases and Database Design#11work of Business tier is distributed between other tiers
اسلاید 12: Popular RDBMSsMicrosoft Accessaimed at small businesses, and useful for desktop applications and systems with a small number of usersOraclescalable and secure, and widely used by large organisationsMySQLopen-source and quite powerful, widely used in web sitesJavaDBa compact DBMS written in Java, and suitable for mobile devices in particular...and many more COMU114 Introduction to Database Development 1. Databases and Database Design#12
اسلاید 13: RDBMS toolsMost RDBMSs include tools to create complete application, for example:form designers – to allow data entry forms to be created for the user interfacereport designers – to present data to the userstored procedures – to perform processing of data according to business rules COMU114 Introduction to Database Development 1. Databases and Database Design#13
اسلاید 14: RDBMS and other toolsCan use your RDBMS and its tools for everything, or Can use the RDBMS as a component and use other tools and programming languages to create the other componentsFor example the GCUTours case study:data entry forms and reports are created as web pages business logic uses Java COMU114 Introduction to Database Development 1. Databases and Database Design#14
اسلاید 15: SQL – the language of relational databasesTo develop applications which use relational databases you usually need to use SQL Structured Query LanguageThis is the language which is used to define queriesA query is a request to a DBMS for some specific informationRelational databases are sometimes referred to as SQL databases COMU114 Introduction to Database Development 1. Databases and Database Design#15
اسلاید 16: SQL exampleSQL queries can be quite easy to understandFor example, the following query finds the last name of all the customers in a database:SELECT lastName FROM Customers;SQL can also be used to add, update or delete data, and to build the database in the first place COMU114 Introduction to Database Development 1. Databases and Database Design#16
اسلاید 17: SQL standardsSQL is supposed to be a standard language which is supported by all RDBMSsIn fact, you need to be careful because there are some important differences between the versions of SQL used by different systemsDifferent versions of SQL standards (SQL92, SQL99,etc.)Different implementations by RDBMS vendors COMU114 Introduction to Database Development 1. Databases and Database Design#17
اسلاید 18: Designing a databaseA well-designed database helps to make sure that the data stored is accurate and consistent and can be retrieved easilyWhat do we mean by inconsistencies? It would, for example, be inconsistent to store a booking without storing the details of the customer making the bookingWith careful design, we can make sure the database won’t allow this to happen COMU114 Introduction to Database Development 1. Databases and Database Design#18
اسلاید 19: Steps in designing a databaseDetermining the intended uses of the systemCreating a data modelImplementing the database COMU114 Introduction to Database Development 1. Databases and Database Design#19
اسلاید 20: The domain modelData model = domain model COMU114 Introduction to Database Development 1. Databases and Database Design#20
اسلاید 21: Data modelling techniquesWe are using object-oriented techniques with UML to design our data modelThere are other methods which are also commonly used in database designOne widely used method is called Entity Relationship Modelling (ERM)Represents the data model as an Entity Relationship Diagram (ERD) COMU114 Introduction to Database Development 1. Databases and Database Design#21
اسلاید 22: From data model to databaseNeed to consider how the data model can be represented in a specific RDBMSThis requires some further designRDBMS software has specific ways of representing and enforcing the entities, attributes and relationships in the data modelFor example, a data model entity is represented as a table in the relational database COMU114 Introduction to Database Development 1. Databases and Database Design#22
اسلاید 23: Representing the data model in an RDBMS COMU114 Introduction to Database Development 1. Databases and Database Design#23
اسلاید 24: Different representationsbusiness tierfor example as Java classes and objects business logic in Java methodsdatabase tierdata is stored permanently in a databasesystem queries database to get data it needs to carry out a particular actionThe system needs to map data from database tables to classes COMU114 Introduction to Database Development 1. Databases and Database Design#24
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