Tutorial 3 - Answers about DBMS (Database System Development Lifecycle) PDF

Preview

Summary

Answers about DBMS (Database System Development Lifecycle)...

Description

CN/CD 5000 Database Systems 2020-2021

Tutorial 3 Topic 3- Database System Development Lifecycle Tutorial Questions (2 mark)

1. What are the main stages of the database system development lifecycle? Depict the stages using www.draw.io. For each stage, state if it is mandatory or optional. I have been having problems with draw.io therefore I have to write the diagram out. The Database system lifestyle is the way in which a database is created and this has specific steps to make the database. The steps are as followed: - Database planning: this step means briefly planning what the database is going to be solving, so this could be a database for transaction records or a UEL modules. - System Definition: the mission statement is created here and the database is explained in more detail and started to think how exactly the database is going to be formed and compiled. - Requirement collection and analysis: now that the creators have created their mission statement, they can start to think what exactly they need for the database so if this was a UEL Module database then they would need the names of students. This stage is all about collection the information that is necessary. - Database Design: This is a very important stage as it defines how the database is going to be linked together and how the information can be shown. This also ties into the structure of the data, so could be shown on a hierarchy or a top down model. - DBMS Selection: This is all about the software that is going to be used in the process of the Database’s final stage. (optional) - Application design/ prototyping: This carries on from the database design, but this creating the first attempt at the database. - Implementation: This is trailing the database made in the stage before. However, this can be done in different ways. For example, this could be alongside the old system or that could be taken down and only the new system is used. - Testing: After the database has been implemented, then there must be tests by users, or testers so that they can identify problems if there are. - Operational maintenance: When the database has went through all the creating, designing and testing stages it can then be maintained through updates and changes every so often, there isn’t much that has to happen with the database until it becomes retired.

2. What are the main causes of software depression? The main causes of Software depression are usually because of the following; over budget, unreliable, difficult to maintain and because they have performed poorly. In the past, this has been referred to as the software crisis, but now it referred to as the software depression.

3. Discuss the main approaches to database design. Discuss the contexts where each is appropriate.

CN/CD 5000 Database Systems 2020-2021

The main approaches to database design we have discussed are bottom-up and top down. Top down is a hierarchy which means it shows the top level to the bottom level, and usually indicated there are more users/information at the bottom of the design. For example, in a Store there will be a branch manager, to a store manager, to a section manager, to team members. This would be easily shown in a diagram because it would have more users at the bottom compared to the top. On the other hand, bottom-up identifies the attributes for the users and then use this information to create a group of entities. This then means that the conceptual data is at the top of the design. These two design types are similar, but the thought process behind them has been flipped.

4. In the context of database planning, what is a “mission statement”? A mission statement is what the database is being set out to do, this would be a brief description that lets the team know what they are creating. This could be the targeted users, what data is going to be stored in the database.

5. What are the three phases of database design? How are they related to each other? Conceptual, Logical and Physical Conceptual database design is making the database, including the entities, relationships and attributes for each user to be assigned. This usually has a lot of 1s and 0s. Logical database design is the design of how the database is going to link together and to form the relations, logically. Physical database design is deciding how the database is going to be implemented. Each phase links to the stage before because you cannot complete the logical phase as you need to know the entities and attributes to create the foreign key to link different tables and database sections to each other.

6. The following are problems that have been identified during the testing process in the development of a new system. In which part of the life cycle do you think these problems could have originated and been identified by a thorough review following that stage in the development life cycle? a) The performance of the system is poor – failing to respond quickly enough to meet the stated user requirement of interactive, screen-based use.

CN/CD 5000 Database Systems 2020-2021

Testing Stage

b) No backup facilities were included to meet the users' requirement of long-term archival of their data. Requirement Collection

c) No user manuals were provided! Requirement Stage

7. Discuss what a user view represents in the context of a database system. A user view represents how a user is going to be using the system. For example, this could be how a member of staff is going to use the sales system, so this is very important for the designers to take into account the users need and requirements to create a system that is perfect for them.

8. What is meant by the term transaction? Give an example of a transaction. A transaction is an event that happens within the database, this could be next to anything. For example, this could be adding, deleting, modifying data in the database. A complete transaction is giving the command to the database.

9. What is concurrency control and why does a DBMS need a concurrency control facility? Concurrency control is used for a multi user dmbs system that has simultaneous transactions occurring at the same time, which still needs the database to preserve integrity. This means when there is more than one transaction occurring at the same time

Directions:

CN/CD 5000 Database Systems 2020-2021

1- Avoid Plagiarism 2- Copy Pasting (each other work) is strictly prohibited (will be awarded ‘zero’) 3- Please write the answers in a word file and upload in Moodle in your allotted group (Link is available over Moodle)...