Database Design - Common Question To understanding Database


1.1 What is the purpose of a database?
1.2 What is the most commonly used type of database?
1.3 Give an example of two related tables other than the example used in this book.

1.4 For the tables you created in Review Question

1.3, what are the primary keys of each table? Do you think that any of these primary keys could be surrogate keys?

1.5 Explain how the two tables you provided in Review Question 1.3 are related. Which table contains the foreign key, and what is the foreign key?

1.6 Show your two tables from Review Question 1.3 without the columns that represent the relationships. Explain how the value of your two tables is diminished without the relationships.

1.7 Define the terms data and information. Explain how the two terms differ.

1.8 Give an example of information that could be determined using the two tables you provided in your answer to ReviewQuestion 1.3.

1.9 Give examples of a single-user database application and a multiuser database application other than the ones shown in Figure 1-5.

1.10 What problem can occur when a database is processed by more than one user?

1.11 Give an example of a database application that has hundreds of users and a very large and complicated database. Use an example other than one in Figure 1-5.

1.12 What is the purpose of the largest databases at e-commerce companies such as

1.13 How do the e-commercecompanies use the databases discussedin ReviewQuestion 1.12?

1.14 How do digital dashboard and data mining applications differ from transaction pro- cessing applications?

1.15 Explain why a small database is not necessarily simpler than a large one.

1.16 Explain the components in Figure 1-7.

1.17 What are the functions of application programs?

1.18 What is Structured Query Language (SQL), and why is it important?

1.19 What does DBMSstand for?

1.20 What are the functions of the DBMS?

1.21 Name three vendors of DBMSproducts.

1.22 Define the term database.

1.23 Why is a database considered to be self-describing?

1.24 What is metadata? How does this term pertain to a database?

1.25 What advantage is there in storing metadata in tables?

1.26 List the components of a database other than user tables and metadata.

1.27 Is Microsoft Access a DBMS?Why or why not?

1.28 Describe the components shown in Figure 1-15.

1.29 What is the function of the application generator in MicrosoftAccess?

1.30 What is the name of the DBMSengine within MicrosoftAccess?Why do we rarely hear about that engine?

1.31 Why does Microsoft Access hide important database technology?

1.32 Why would someone choose to replace the native MicrosoftAccess DBMSengine with
SQL Server?

1.33 Name the components of an enterprise-class database system.

1.34 Name and describe the four categories of database applications that would use an enterprise-class database system.
Chapter 1 Introduction 29

1.35 How do database applications read and write database data?

1.36 Name the fiveDBMSproducts described in this chapter, and compare them in terms of power, features, and difficultyofuse.

1.37 List several consequences of a poorly designed database.

1.38 Explain two ways that a database can be designed from existing data.

1.39 What is a data warehouse? What is a data mart?

1.40 Describe the general process of designing a database for a new information system.

1.41 Explain two ways that databases can be redesigned.

1.42 What does the term database migration mean?

1.43 Summarize the various ways that you might work with database technology.

1.44 What job functions does a knowledge worker perform?

1.45 What job functions does a database administrator perform?

1.46 Explain the meaning of the domains in Figure 1-23.

1.4 7 What need drove the development of the first database technology?

1.48 What are Data Language/I and CODASYLDBTG?

1.49 Who was E. F. Codd?

1.50 What were the early objections to the relational model?

1.51 Name two early relational DBMSproducts.

1.52 What are some of the reasons for the success of Oracle Database?

1.53 Name three early personal computer DBMSproducts.

1.54 What happened to the products in your answer to ReviewQuestion 1.53?

1.55 What was the purpose.ofOODBMS products? State two reasons that OODBMSprod•
ucts were not successful

1.56 What characteristic of HTTP was a problem for database processing applications?

1.57 What is an open source DBMS product? Which ·of ti).e five DB'NlS products that you
named in answering Review Question 1.36 is historicallyan open source DBMSproduct?

1.58 What has been the response of companies that sell proprietary DBMSproducts to the open source DBMSproducts? Include two examples in your answer.

1.59 What is XML?What comment did Bill Gates make regarding XML?

1.60 What is the NoSQLmovement? Name two applications that rely on NoSQLdatabases.

Chapter 6

Three major tasks for transforming a data mode into a database design

            The three tasks of transforming a database mode into a database design are as follows.

[blur] 1. Replacement of the entities and attributes with both the tables and the columns.
2. Developing a representation of maximum cardinalities and relationships through the application of the foreign keys.
3. Facilitating the representation of the minimum cardinality through the definition of the specific actions in an attempt to contrast the values of foreign and the primary keys. [/blur]

The relationship between entities and tables? Between attributes and columns

[blur] When developing a database design, an individual creates a table for each of the entity and a column for the attribute. The attribute is a component in a table which describes instances in the form of a row. The entity is the object of a system redesigned to store information and a table has additional information regarding an object, person, or a thing. [/blur]

Why is the choice of the primary key important?

            [blur] The choice of a key is important because a database system is likely to use it to facilitate the process of a search or sort in the rows of a table, in other cases, the key can be used as a way of organising how the table stores information. In addition, the key can also be used by such a database system as a way of creating indexes and any other form of data structure. [/blur]

Characteristics of an ideal primary key?

              [blur] The short characteristic is the first and it refers to its ability to be used as a foreign key in another table, numeric is second focuses on being compact and easy to use when relating to the tables of the same database while fixed is the last characteristic and addresses the challenge of avoiding to change the corresponding foreign key columns in other tables hence making the whole process cumbersome. [/blur]

What is a surrogate key? What are its advantages?

            [blur] A surrogate key is a unique database management system identifier for the rows which can be relied upon as a primary key to the table. Surrogate keys tend to be unique hence making it possible to differentiate the row in a table. This aspect of being unique makes them useful since in comparison to the natural primary keys, surrogate ones do not change and hence they facilitate an individual in making updates. The other advantage of the surrogate key refers to their ability to track down the slowly changing dimension such additional employee details. This is the advantage since surrogate keys facilitate the use of unlimited values and accommodate uniform application of rules. [/blur]

When should you use a surrogate key?

            [blur] The two instances when an individual can use the surrogate keys are when the ideal characteristics of keys are missing in the primary ones such as being short, numeric, and fixed and in instances where there is the lack of additional candidate keys or if by using one an individual feels that the database is still not achieving its objectives with these keys. [/blur]

Describe two disadvantages of a surrogate key

            [blur] The main disadvantages of a surrogate key are making the data transfer harder by requiring that an individual manually attends to the data in the process of importation. The second challenge of such keys arises on its limitation of the rows of a target table since these keys only rely on the positive half of the numeric columns. Other disadvantages are wasted space which arises from additional generated keys columns and increasing skewedness which may affect the performance of queries. [/blur]

What is the difference between an alternate key and a candidate key?

            [blur] Both the alternate and candidate keys are the same and thus do not have any difference. They also are both unique and alternative identifiers in rows and tables. [/blur]

Chapter 8

Why is it important to analyse the database before implementing database redesign tasks what is likely if it is not done?

            [blur] Analysing a database prior to implementation of a redesign is important since it allows an individual to comprehend how any likely structural change might affect entities and relationships. The structure of a database may have a ripple effect on the entities and relationship of an object. A user must thus thoroughly comprehend which object they are to modify. For example, one may modify the tables, key constraints, triggers, application codes, views, application codes, and stored procedures. Such an extensive analysis might provide one with an idea of what he/she needs to address and the areas where it needs to be addressed. [/blur]

Explain the process of reverse engineering

            [blur] Reverse engineering refers to how a data model is obtained from a database. The whole process relies on the standard tools which begin with the capture of information related to the tables and their relationships and presenting such information graphically. [/blur]

Why is it important to carefully evaluate the results of reverse engineering?

[blur] Reverse engineering allows the analysts to comprehend the database structure prior to its redesign. The RE model is built in such a way that it can highlight at once all the tables in a database, the columns, and their properties. Thus, the model allows one to comprehend where an individual should make any change. [/blur]

What is a dependency graph and what purpose does it serve?

            [blur] The dependency graph is a diagram which has nodes and arcs. Its main objective is to present the relationship between the tables, the triggers and views. Dependency graphs help an individual determine the impact of such relationships and the aspects that face such changes. [/blur]

Database Design - Common Question To understanding Database

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