Database Sdlc b6w10

CH2 THE DATABASE DEVELOPMENT PROCESS

06/10/15

Compiled by L. Mutanu

1

CH2 THE DATABASE DEVELOPMENT PROCESS Information Systems Architecture

• This is a blueprint for organization’s desired information systems structure • It consists of: – Data - Enterprise Data Model–simplified ER Diagram – Processes – Data flow diagrams, process decomposition, etc. – Data Network – topology diagram – People – people/ management – Events - when processes are performed – Rules - Reasons for events and e.g. decision tables



The StayHome case study • • • •

This case study describes a company called StayHome. It rents out videos to its . The first branch of StayHome was established in 1982 in Seattle. The company has now grown and has many branches throughout the United States.



StayHome staff registration form StayHome however keeps data about its staff using the Ms word form showed below.



Every branch keeps a list of staff as shown below



Additionally a list of the videos kept in a branch is also maintained



When a new member s StayHome they fill in the registration form below



A list of in the branch is also maintained



When a member rents a video the following information is kept



• You have been asked to develop a DBMS for Stay Home.


CH2 THE DATABASE DEVELOPMENT PROCESS Approaches to Database Development • SDLC - System Development Life Cycle – Detailed, well-planned development process – Time-consuming, but comprehensive • Prototyping - Rapid application development (RAD) – Defines database during development of initial prototype – Repetition of implementation and testing activities with new prototype versions



Systems Development Life Cycle

Planning Analysis Logical Design Physical Design Implementation Maintenance Compiled by L. Mutanu

CH2 THE DATABASE DEVELOPMENT PROCESS Systems Development Life Cycle Purpose–preliminary understanding of the system

Planning Planning

Analysis Logical Design Physical Design Implementation Database activity– enterprise modeling (Processes/Activities?) Compiled by L. Mutanu

Maintenance


StayHome case study – database planning • Defines the major aims of the database system. • specifies, in general , the work to be done, the resources with which to do it, and the money to pay for it all.



Systems Development Life Cycle Purpose– Identify possible solution and select the best .

Planning Analysis Analysis

Logical Design Physical Design Database activity–conceptual data modeling (What Data?)


Implementation Maintenance


StayHome case study – Analysis

• What data will the database have? Identify entities. •Branches •Staff •Video • •Rentals •Suppliers •Supplier Orders


CH2 THE DATABASE DEVELOPMENT PROCESS Systems Development Life Cycle Purpose– Creation on paper or with CASE tools

Planning Analysis

Logical Design Logical Design

Physical Design Database activity– design transactions, forms, displays, views, data integrity and security How is data manipulated? Compiled by L. Mutanu



StayHome Case Study – Logical Design

• What activities will be conducted on the data? •Maintaining/Edit – Enter, Update and Delete •Querying – Searching for analysis •Reporting - For Decision making purposes


CH2 THE DATABASE DEVELOPMENT PROCESS Systems Development Life Cycle Purpose– Identify and acquire technology

Planning Analysis

Logical Design Physical PhysicalDesign Design Database activity– physical database design (define database to DBMS, physical data organization, database processing programs) Compiled by L. Mutanu



StayHome Case Study – Physical Design

• CASE Tools? • Open Source? Commercial DBMS? • In house development? Outsource? • Which DBMS/Application?


CH2 THE DATABASE DEVELOPMENT PROCESS Systems Development Life Cycle Purpose–programming, testing, training, installation, documenting

Planning Analysis Logical Design Physical Design Implementation Implementation Database activity – writing, coded programs, documentation, installation and conversion Compiled by L. Mutanu

Maintenance

CH2 THE DATABASE DEVELOPMENT PROCESS Systems Development Life Cycle

Purpose–monitor, repair, enhance

Planning Analysis

Logical Design Physical Design Implementation Database activity– database maintenance, tuning, error corrections Compiled by L. Mutanu

Maintenance Maintenance

CH2 THE DATABASE DEVELOPMENT PROCESS Prototyping Database Methodology


CH2 THE DATABASE DEVELOPMENT PROCESS Database Schema • The schema of a database system is its structure. In a relational database, the schema defines the tables, the fields, relationships, etc. • The Three-Schema Architecture is the most popular. It contains: • External Schema - Views. Determined from businessfunction/data entity matrices. It is a subsets of Conceptual Schema • Conceptual Schema – Data s view. Combines different external views into a single view. • Internal Schema – This is the underlying design and implementation . It consists of two different schemas: – Logical structures – Shows the data structure – Physical structures – Shows how the data is stored Compiled by L. Mutanu





CH2 THE DATABASE DEVELOPMENT PROCESS Data Independence • Logical Data Independence Refers to immunity of external schemas to changes in conceptual schema. Conceptual schema changes (e.g. addition/removal of entities) should not require changes to external schema or rewrites of application programs. • Physical Data Independence Refers to immunity of conceptual schema to changes in the internal schema. Internal schema changes (e.g. using different file organizations, storage structures/devices). Should not require change to conceptual or external schemas.





• The ThreeLevel Architecture offers the following benefits: – All s should be able to access same data. – A ’s view is immune to changes made in other views. – s do not need to know physical database storage details.



Developing three-schema architecture for a database



StayHome case study – External Schema • Gather more details on views to create s’ requirements specification, which describes data to be held in database and how data is to be used. • Which are the different s of the system? • What data do they want? • What can they do with the data; Edit, Query or simply view?

•Overall Manager •Branch supervisors •Customer Compiled by L. Mutanu


CRUD Matrix



StayHome case study – Internal Schema • Collect general requirements to create the system - systems specification • Describes features to be included in new database system such as networking, shared access, performance, and security requirements.


CH2 THE DATABASE DEVELOPMENT PROCESS Multi DBMS Architectures 1. 2. 3.

Teleprocessing Fileserver Clientserver


CH2 THE DATABASE DEVELOPMENT PROCESS 1. Teleprocessing

• Traditional architecture. Was a single mainframe with a number of terminals attached.


CH2 THE DATABASE DEVELOPMENT PROCESS 2. FileServer • Fileserver is connected to several workstations across a network. The database resides on fileserver. DBMS and applications run on each workstation. Disadvantages include: •Significant network traffic. •Copy of DBMS on each workstation. •Concurrency control more complex.


CH2 THE DATABASE DEVELOPMENT PROCESS 3. ClientServer • Server holds the database and the DBMS. • Client manages and runs applications. • Advantages include: – wider access to existing databases; – increased performance; – possible reduction in hardware costs; – reduction in communication costs; – increased consistency.



Three-tiered Client-Server Database Architecture



StayHome case study – DBMS Architecture • Decide how to manage a project where database system has more than one view.


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