CH5_ARQ_DahalPandey Januka
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Chapter 5- Active Review Question
Name: Januka Dahal Pandey
Date: September 21, 2023
Q5-1 What is the purpose of a database? State the purpose of a database. The purpose of a database is to keep track of things. Explain the circumstances in which a database is preferred to a spreadsheet.
Lists that involve data with multiple themes require a database. For example: The database has multiple themes; it shows student grades, student emails, and student office visits. Describe the key difference between Figures 5-1 and 5-2. The key distinction between Figures 5-1 and 5-2 is that the data in Figure 5-1 is about a single theme or concept. It is about student grades only. The data in Figure 5-2 has multiple themes; it shows student grades, student emails, and student office visits. We can make a general rule from these examples: Lists of data involving a single theme can be stored in a spreadsheet; lists that involve data with multiple themes require a database. Q5-2 What is a database? Define the term database
. A database is a self-describing collection of integrated records. Explain the hierarchy of data and name three elements of a database. A byte is a character of data. Which is on the base line. In databases, bytes are grouped into columns
, such as Student Number and Student Name
. Columns are also called fields
, which is on second from buttom. Columns or fields, in turn, are grouped into rows
, which are also called records
which is on third from buttom. The collection of data for all columns (
Student Number, Student Name, HW1, HW2
, and MidTerm
) is called a row or a record
. Finally, a group of similar rows or records is called a table or a file
. Define metadata
. A database is a collection of tables plus relationships among the rows in those tables, plus special data, called metadata.
Using the example of Student and Office_Visit tables, show how relationships among rows are represented in a database. Consider the terms on the left-hand side of Figure 5-5. You know what tables are. To understand what is meant by relationships among rows in tables
, examine Figure 5-6. It shows sample data from the three tables Email, Student
, and Office_Visit
. Notice the column
named Student Number in the Email table. That column indicates the row in Student to which a row of Email is connected. In the first row of Email
, the Student Number value is 1325. This indicates that this particular email was received from the student whose Student Number is 1325. If you examine the Student table, you will see that the row for Andrea Baker has this value. Thus, the first row of the Email table is related to Andrea Baker. 1
Chapter 5- Active Review Question
Name: Januka Dahal Pandey
Date: September 21, 2023
Define the terms primary key, foreign key
, and relational database
. A key (also called a primary key
) is a column or group of columns that identifies a unique row in a table. The columns that fulfill a role like that of Student Number in the Email and Office Visit tables
are called foreign keys
. This term is used because such columns are keys, but they are keys of a different (foreign) table than the one in which they reside.
Databases that carry their data in the form of tables and that represent relationships using foreign keys are called relational databases
. (The term relational is used because another, more formal name for a table like those we’re discussing is relation
.) Q5-3 What is a database management system (DBMS)? Explain the acronym DBMS and name its functions. A database management system (DBMS) is a program used to create, process, and administer a database. List five popular DBMS products. MariaDB, Popular DBMS products are DB2 from IBM, Access and SQL Server from Microsoft, Oracle Database from the Oracle Corporation, MySQL
, an open source DBMS product Explain the difference between a DBMS and a database. A DBMS is a software program; a database is a collection of tables, relationships, and metadata. Summarize the functions of a DBMS. Creating the Database and Its Structures, Processing the Database, Administering the Database Define SQL
. Structured Query Language (SQL) is an international standard language for processing a
database. Describe the major functions of database administration. DBMS administrative functions include backing up database data, adding structures to improve the performance of database applications, removing data that are no longer wanted
or needed, and similar tasks. Q5-4 How do database applications make databases more useful? Explain why database tables, by themselves, are not very useful to business users. 2
Chapter 5- Active Review Question
Name: Januka Dahal Pandey
Date: September 21, 2023
A set of database tables, by itself, is not very useful; the tables in Figure 5-6 contain the data the professor wants, but the format is awkward at best. The data in database tables can be made more useful, or more available for the conception of information, when it is placed into forms like that in Figure 5-2 or other formats. Name the four elements of a database application and describe the purpose of each. Forms View data; insert new, update existing, and delete existing data.
Reports Structured presentation of data using sorting, grouping, filtering, and other operations.
Queries Search based on data values provided by the user.
Application programs Provide security, data consistency, and special purpose processing, (e.g., handle out-of-stock situations).
Explain the difference between a database application and a database application program. Application programs Provide security, data consistency, and special purpose processing, (e.g., handle out-of-stock situations)
Database applications are based on newer technology that employs browsers, the Web, and related standards. These browser-based applications can do everything the older ones do, but they are more dynamic and better suited to today’s world. To see why, consider each type. Describe the nature of traditional database applications. A traditional database is shared among many users. In that case, the application resides on the users’ computers and the DBMS and database reside on a server computer. A network, in most cases not the Internet, is used to transmit traffic back and forth between the users’ computers and the DBMS server computer. Traditional report, which is a static display of data, placed into a format that is meaningful to the user. Explain why browser-based applications are better than traditional ones. Name the primary technologies used to support browser-based applications. The databases in browser-based applications are nearly always shared among many users. The users’ browsers connect over the Internet to a Web server computer, which in turn connects to a database server computer (often many computers are involved on the server side of the Internet). Browser database application forms, reports, and queries are displayed
and processed using html and, most recently, using html5, css3, and JavaScript.
Q5-5 How are data models used for data- base development? Explain why user involvement is critical during database development. Because the design of the database depends entirely on how users view their business environment, user involvement is critical for database development. Think about the Student data- base. What data should it contain? Possibilities are Students, Classes, Grades, Emails, Office_Visits, Majors, Advisers, Student_Organizations
—the list could go on and on. Further, how much detail should be included in each? Should the database include campus addresses? Home addresses? Billing addresses 3
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Chapter 5- Active Review Question
Name: Januka Dahal Pandey
Date: September 21, 2023
Describe the function of a data model. Database structures can be complex, in some cases very complex. So, before building the data- base the developers construct a logical representation of database data called a data model
. Sketch the data- base development process. Define E-R model, entity, relationship, attribute
, and identifier
. The entity-relationship (E-R) data model is a tool for constructing data models. Developers use it to describe the content of a data model by defining the things (
entities
) that will be stored in the database and the relationships among those entities. An entity is something that the users want to track. Examples of entities are Order, Customer, Salesperson
, and Item
. Entities have attributes that describe characteristics of the entity. Example attributes of Order are OrderNumber, OrderDate, SubTotal, Tax, Total
, and so forth. Example attributes of
Salesperson are SalespersonName, Email, Phone
, and so forth. Entities have an identifier
, which is an attribute (or group of attributes) whose value is associated with one and only one entity instance. Give an example, other than one in this text, of an E-R diagram. Too cumbersome for use in database design discussions. Instead, database designers use diagrams called entity-relationship (E-R) diagrams
. There are rectangles for the Department, Adviser
, and Student entities.
Define maximum cardinality and minimum cardinality
. Give an example of three maximum cardinalities and two minimum cardinalities. The crow’s-foot notation shows the maximum number of entities that can be involved in a relationship. Accordingly, they are called the relationship’s maximum cardinality
. Common examples of maximum cardinality are 1:N, N:M, and 1:1 Another important question is “What is the minimum number of entities required in the relationship?” Must an adviser have a student to advise, and must a student have an adviser? Constraints on minimum requirements are called minimum cardinalities
. Explain the notation in Figures 5-20 and 5-21. If there are two vertical bars, both the minimum and maximum cardinality are one. If there is a vertical bar with a crow’s foot, then the minimum cardinality is one and the maximum is many. Q5-6 How is a data model transformed into a database design? 4
Chapter 5- Active Review Question
Name: Januka Dahal Pandey
Date: September 21, 2023
Name the three components of a database design. Database design is the process of converting a data model into tables, relationships, and data constraints. The database design team transforms entities into tables and expresses relationships by defining foreign keys. Database design is a complicated subject; as with data modeling, it occupies weeks in a database management class. Define normalization and explain why it is important. Normalization is the process of converting a poorly structured table into two or more well-
structured tables. A table is such a simple construct that you may wonder how one could possibly be poorly structured. In truth, there are many ways that tables can be malformed—
so many, in fact, that researchers have published hundreds of papers on this topic alone. Define data integrity problem and describe its consequences. Give an example of a table with data integrity problems and show how it can be normalized into two or more tables that
do not have such problems. Suppose the Accounting name change is correctly made in two rows, but not in the third. The result is shown in Figure 5-22b. This table has what is called a data integrity problem: Some rows indicate that the name of Department 100 is “Accounting and Finance,” and another row indicates that the name of Department 100 is “Accounting.” Data integrity problems are serious. A table that has data integrity problems will produce incorrect and inconsistent results. Users will lose confidence in the data, and the system will develop a poor reputation. Information systems with poor reputations become serious burdens to the organizations that use them. Describe two steps in transforming a data model into a database design. Using an example not in this chapter, show how 1:N and N:M relationships are represented in a relational database. The steps involved in transforming a data model into a relational database design. First, the database designer creates a table for each entity. The identifier of the entity becomes the key to the table. Each attribute of the entity becomes a column of the table. Next, the resulting tables are normalized so that each table has a single theme. Once that has been done, the next step is to represent the relationships among those tables. Describe the users’ role in the database development. A database is a model of how the users view their business world. This means that the users are the final judges as to what data the database should contain and how the records in that
database should be related to one another. Explain why it is easier and cheaper to change a data model than to change an existing database. Use the examples of Figures 5-25c and 5-26c in your answer. The easiest time to change the database structure is during the data modeling stage. Changing a relationship from one-to-many to many-to-many in a data model is simply a matter of changing the 1:N notation to N:M. However, once the database has been constructed and loaded with data and forms, reports, queries, and application programs have been created, changing a one-to-many relationship to many-to-many means weeks of work. 5
Chapter 5- Active Review Question
Name: Januka Dahal Pandey
Date: September 21, 2023
Q5-7 How can eHermes benefit from a database system? Summarize the two database architectures that eHermes could use for its image database. Describe the architecture it used and explain the rationale for that choice.
For the first one, it can store the images on a file server and keep metadata about each image in a relational database that it can query. That metadata will include the address of the image on the file server. Alternatively, eHermes can utilize one of the new NoSQL DBMS products like MongoDB
—an open source document-oriented DBMS—to store the images in the same database as the metadata. Q5-8 2029? Explain how an increase in database data in the next decade will affect business intelligence
and security. With ever-cheaper data storage and data communications, we can be sure that the volume of database data will continue to grow, probably exponentially, through 2029. Summarize two major requirements that some Internet database applications created. The DBMS landscape is changing. While for years relational DBMS products were the only game in town, the Internet changed that by posing new processing requirements. As compared to traditional database applications, some Internet applications process many, many more transactions against much simpler data. A tweet has a much simpler data structure than the configuration of a Kenworth truck, but there are so many more tweets than truck configurations! Explain the characteristics of the ACID processing of a transaction. Traditional relational DBMS products devote considerable code and processing power to support what are termed ACID (atomic, consistent, isolated, durable) transactions. In essence, this acronym means that either all of a transaction is processed or none of it is (atomic), that transactions are processed in the same manner (consistent) whether processed alone or in the presence of millions of other transactions (isolated), and that once a transaction is stored it never goes away— even in the presence of failure (durable). Briefly describe the characteristics of NoSQL, NewSQL, and in-memory DBMS products. Summarize how you should respond to these developments. NoSQL DBMS
. This acronym is misleading. It really should be non-relational DBMS. It refers to new DBMS products that support very high transaction rates processing relatively simple data structures, replicated on many servers in the cloud, without ACID transaction support. MongoDB, Cassandra, Bigtable, and Dynamo are NoSQL products. NewSQL DBMS
. These DBMS products process very high levels of transactions, like the NoSQL DBMS, but provide ACID support. They may or may not support the relational model. Such products are a hotbed of development with new vendors popping up nearly every day. Leading products are yet unknown. 6
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Chapter 5- Active Review Question
Name: Januka Dahal Pandey
Date: September 21, 2023
In-memory DBMS
. This category consists of DBMS products that process databases in main memory. This technique has become possible because today’s computer memories can be enormous and can hold an entire database at one time, or at least very large chunks of it. Usually, these products support or extend the relational model. SAP HANA is a computer with an in-memory DBMS that provides high volume ACID transaction support simultaneously with complex relational query processing. Tableau Software’s reporting products are supported by a proprietary in-memory DBMS using an extension to SQL. 7