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2.1 Introduction to Database 46 2.1.1.3 Database management systems (DBMS) A Database Management System (DBMS) is the software system that allows users to define, create, maintain and control access to the database. DBMS makes it possible for end users to select, insert, update and delete data in database. DBMS were developed to address the file system’s inherent weaknesses. A DBMS provides these advantages: • Improved data sharing. The DBMS helps create an environment in which end users have better access to more and better-managed data. Such access makes it possible for end users to respond quickly to changes in their environment. • Improved data security. The more users access the data, the greater the risks of data security breaches. Corporations invest considerable amounts of time, effort, and money to ensure that corporate data is used properly. A DBMS provides a framework for better enforcement of data privacy and security policies. • Better data integration. Wider access to well-managed data promotes an integrated view of the organization’s operations and a clearer view of the big picture. It becomes much easier to see how actions in one segment of the company affect other segments. • Minimized data inconsistency. Data inconsistency exists when different versions of the same data appears in different places. For example, data inconsistency exists when a company’s sales department stores a sales representative’s name as Bill Brown and the company’s personnel department stores that same person’s name as William G. Brown. The probability of data inconsistency is greatly reduced in a properly designed database. • Improved data access. The DBMS makes it possible to produce quick answers to ad hoc queries. From a database perspective, a query is a specific request issued to the DBMS for data manipulation—for example, to select or update the data. • Improved decision making. Better-managed data and improved data access make it possible to generate better-quality information, on which better decisions are based. The quality of the information generated depends on the quality of the underlying data. Data quality is a comprehensive approach to promoting the accuracy, validity, and timeliness of the data.

2.1 Introduction to Database 47 • Increased end-user productivity. The availability of data, combined with the tools that transform data into usable information, empowers end users to make quick, informed decisions that can make the difference between success and failure in the global economy. Examples of DBMS: • LibreOffice Base • MS Access • MS SQL Server • IBM DB2 • MySQL • Oracle RDBMS 2.1.2 File Processing Systems and The Database System (T2C2) Almost all application programs use the file processing approach, the database approach, or a combination of both approaches to store and manage data. File Processing Systems A file processing system is a filing system which each department or area within an organization has its own set of files. • In the past, many organizations exclusively used file processing systems to store and manage data. • In a typical file processing system, each department or area within an organization has its own set of files. The records in one file may not relate to the records in any other file. • Organizations have used file processing systems for many years. Many of these systems, however, have two major weaknesses: they have redundant data and they isolate data. o Data Redundancy — Each department or area in an organization has its own files in a file processing system. Thus, the same fields are stored in multiple files. o Isolated Data — Often it is difficult to access data stored in separate files in different departments.

2.1 Introduction to Database 48 The Database Approach A database approach is an approach which many programs and users share the data in the database. • When an organization uses a database approach, many programs and users share the data in the database. • A school’s database most likely at a minimum contains data about students, instructors, schedule of classes, and student schedules. Various areas within the school share and interact with the data in this database. • The database does secure its data, however, so that only authorized users can access certain data items. Difference between file processing systems and the database system: The primary differences between the two are: • How the data is stored and manipulated? • Who can access the data? • How much data can be stored? File Processing Systems Database System Description Each department or area within an organization has its own set of files. Many programs and users share the data in the database. How the data is stored and manipulated File processing systems were originally designed for single user. Databases are designed to hold much larger collections of organized information—massive amounts, sometimes. Who can access the data They’re great for a single user or small number of users who don’t need to do a lot of incredibly complicated data manipulation. Databases allow multiple users at the same time to quickly and securely access and query the data using highly complex logic and language. How much data can be stored Relatively smaller amount of data Relatively larger amount of data

2.1 Introduction to Database 49 2.1.3 Advantages and Disadvantages of Using Database System (T1C2) Advantages of using database system Reducing Data Redundancy Most data items are stored in only one file, which greatly reduces duplicate data. Improved Data Integrity When users modify data in the database, they make changes to one file instead of multiple files. Data integrity means that the data is accurate and consistent in the database. All of these databases contain data that is visible to multiple users. So it is necessary to ensure that the data is correct and consistent in all the databases and for all the users. Sharing of Data The data in a database environment belongs to and is shared, usually over a network, by the entire organization. In a database, the users of the database can share the data among themselves. There are various levels of authorization to access the data, and consequently the data can only be shared based on the correct authorization protocols being followed. Many remote users can also access the database simultaneously and share the data between themselves. Easier access The database approach allows nontechnical users to access and maintain data, providing they have the necessary privileges. Many computer users also can develop smaller databases themselves, without professional assistance. Reduced development time It often is easier and faster to develop programs that use the database approach. Many DBMSs include several tools to assist in developing programs, which further reduces the development time. Data Security Data Security is vital concept in a database. Only authorized users should be allowed to access the database and their identity should be authenticated using a username and password. Unauthorized users should not be allowed to access the database under any circumstances as it violates the integrity constraints.

2.1 Introduction to Database 50 Privacy The privacy rule in a database means only the authorized users can access a database according to its privacy constraints. There are levels of database access and a user can only view the data he is allowed to. For example - In social networking sites, access constraints are different for different accounts a user may want to access. Backup and Recovery Database Management System automatically takes care of backup and recovery. The users don't need to backup data periodically because this is taken care of by the DBMS. Moreover, it also restores the database after a crash or system failure to its previous condition. Data Consistency Data consistency is ensured in a database because there is no data redundancy. All data appears consistently across the database and the data is same for all the users viewing the database. Moreover, any changes made to the database are immediately reflected to all the users and there is no data inconsistency. Disadvantages of using database system High Complexity A database can be more complex than a file processing system. People with special training usually develop larger databases and their associated applications. Databases also require more memory, storage, and processing power than file processing systems. Database handling staff required Database and DBMS are quite complex. Hence, skilled personnel are required to handle the database so that it works in optimum condition. This is a costly venture as these professionals need to be very well paid. More Vulnerable due to Database Failure Data in a database can be more vulnerable than data in file processing systems. A database can store a lot of data in a single file. Many users and programs share and depend on this data. If the database is not operating properly or is damaged or destroyed, users may not be able to perform their jobs. Furthermore, unauthorized users potentially could gain access to a single database file that contains personal and confidential data. To protect their valuable database resource, individuals and companies should establish and follow security procedures.

2.1 Introduction to Database 51 Huge Size A database contains a large amount of data, especially for bigger organisations. This data may even increase as more data is updated into the database. All of these leads to a large size of the database. The bigger the database is, it is more difficult to handle and maintain. It is also more complex to ensure data consistency and user authentication across big databases. More Costly Creating and managing a database is quite costly. High cost software and hardware is required for more memory and processing power compared to file processing systems. Also highly trained staff is required to handle the database and it also needs continuous maintenance. All of these ends up making a database quite a costly venture. High Hardware Cost A database contains vast amount of data. So a large disk storage is required to store all this data. Sometimes extra storage may even be needed. All this increases hardware costs by a lot and makes a database quite expensive. Upgradation Costs Often new functionalities are added to the database, this leads to database upgradations. All of these upgradations cost a lot of money. Moreover it is also quite expensive to train the database managers and users to handle these new upgradations. Cost of Data Conversion If the database is changed or modified in some manner, all the data needs to be converted to the new form. This cost may even exceed the database creation and management costs sometimes. This is the reason most organisations prefer to work on their old databases rather than upgrade to new ones.

2.1 Introduction to Database 52 2.1.4 Components of Database Environment (T1C1) The database system is composed of the five (5) major parts; hardware, software, people, procedures, and data. Hardware Hardware refers to all of the system’s physical devices, including computers (PCs, tablets, workstations, servers, and supercomputers), storage devices, printers, network devices (hubs, switches, routers, fiber optics), and other devices (automated teller machines, ID readers, and so on). Software Although the most readily identified software is the DBMS itself, three types of software are needed to make the database system function fully: operating system software, DBMS software, and application programs and utilities. • Operating system software manages all hardware components and makes it possible for all other software to run on the computers. • DBMS software manages the database within the database system. • Application programs and utility software are used to access and manipulate data in the DBMS and to manage the computer environment in which data access and manipulation take place. o Application programs are most commonly used to access data within the database to generate reports, tabulations, and other information to facilitate decision making. o Utilities are the software tools used to help manage the database system’s computer components. For example, all of the major DBMS vendors now provide graphical user interfaces (GUIs) to help create database structures, control database access, and monitor database operations. People This component includes all users of the database system. On the basis of primary job functions, five types of users can be identified in a database system: system administrators, database administrators, database designers, system analysts and programmers, and end users. • System administrators oversee the database system’s general operations. • Database administrators, also known as DBAs, manage the DBMS and ensure that the database is functioning properly. • Database designers design the database structure. They are, in effect, the database architects. If the database design is poor, even the best application programmers and the most dedicated DBAs cannot produce a useful database environment.

2.1 Introduction to Database 53 Because organizations strive to optimize their data resources, the database designer’s job description has expanded to cover new dimensions and growing responsibilities. • System analysts and programmers design and implement the application programs. They design and create the data-entry screens, reports, and procedures through which end users access and manipulate the database’s data. • End users are the people who use the application programs to run the organization’s daily operations. For example, sales clerks, supervisors, managers, and directors are all classified as end users. High-level end users employ the information obtained from the database to make tactical and strategic business decisions. Procedures Procedures are the instructions and rules that govern the design and use of the database system. • Procedures are a critical, although occasionally forgotten, component of the system. Procedures play an important role in a company because they enforce the standards by which business is conducted within the organization and with customers. • Procedures also help to ensure that companies have an organized way to monitor and audit the data that enter the database and the information generated from those data. Data The word data covers the collection of facts stored in the database. Because data is the raw material from which information is generated, determining which data to enter into the database and how to organize that data is a vital part of the database designer’s job.

2.1 Introduction to Database 54 Exercise 2.1 Introduction to Database 1 Define each of the following terms: (a) File processing systems: A filing system which each department or area within an organization has its own set of files. (b) Database: An organized collection of data stored and accessed electronically. (c) Database Management System (DBMS): The software system that allows users to define, create, maintain and control access to the database. 2 Differentiate between file processing systems and the database system. File processing systems designed for single user which relatively can store smaller amount of data. Databases are designed for multiple user to hold much larger collections of organized information. 3 Describe two (2) advantages of using database system. Reducing Data Redundancy, Improved Data Integrity 4 Describe two (2) disadvantages of using database system. High complexity, Vulnerable due to database failure 5 Explain five (5) components of database environment. Hardware: all of the system’s physical devices, including computers. Software: make the database system function fully. People: includes all users of the database system. Procedures: instructions and rules that govern the design and use of the database system. Data: the collection of facts stored in the database.

2.2 Basic concept of Database 55 2.2 Basic Concept of Database Learning Outcomes: At the of this lesson, students should be able to: (a) Apply the basic concepts of database: data hierarchy, entity relationship, data type, data dictionary, entity relationship model. (b) Describe the representations of a relational database: field, record and table/ file (c) Explain the concept of data integrity. (d) Explain the functions of database object. (Table, Query, Form, Report) 2.2.1 Basic Concepts of Database (T6C2) The basic concept of database includes • Data Hierarchy • Data Type • Data Dictionary • Entity Relationship • Entity Relationship Model Data Hierarchy Data in a database has a definite hierarchy. Data hierarchy is the systematic organization of data, often in a hierarchical form. Data organization involves bit, byte, characters, fields, records, files and database. Bit A bit is the smallest unit of data the computer can process. Example: 0 or 1 Byte A byte is eight (8) bits grouped together in a unit. Example: 11010011 Character A character is represented by one (1) byte. Example: ` ~ 1 ! 2 @ 3 # q Q | \ ? / " “ ‘ '

2.2 Basic concept of Database 56 Field At the lowest level, characters are entered into database fields (columns), which hold single pieces of data in the database, such as product names or quantities. A field is a combination of one or more related characters or bytes and is the smallest unit of data a user accesses. It consists of field name, field type / data type, and field properties. *Reminder: A bit is the smallest unit of data the computer can process. Record At the next level are records (rows)—groups of related fields (such as all the fields for a particular student). A primary key is a field that uniquely identifies each record in a file. The data in a primary key is unique to a specific record (eg: Matric Number). Example: Matric Number Name Gender ID DOB Email State ID Stream ID MS0001 Abdullah bin Ibrahim 1 01/01/2004 [email protected] 07 DF MS0002 Aminah binti Wahab 2 29/02/2004 [email protected] 02 DH MS0003 Khadijah binti Muhammad 2 31/12/2004 [email protected] 02 DK MS0004 Abdullah bin Ibrahim 1 31/12/2004 [email protected] 09 DH File / Table At the next level are tables, which are made up of related records stored on a storage medium, such as a hard drive, or on cloud storage. Example: Student File, Lecturer File, Course File, Enrollment File, Gender File, Module File, State File. Database At the top of the hierarchy is the database, which consists of a group of related tables. Files are integrated into a database. This is done using a DBMS. Example: KMK database, School database, Company database, Hospital database

2.2 Basic concept of Database 57 Data dictionary Data dictionary is the repository of all data definitions in a database. Data definition involves describing the properties of the data that go into each database table, specifically the fields that make up the database. A tables is another way of representing entities. During the data definition process, the following are supplied for each field: • Field name (must be unique within the table). o A field name uniquely identifies each field. When searching for data in a database, you often specify the field name. o Example: Matric Number, Name, Gender ID, DOB, Email, State ID, Stream ID o Primary key is an attribute or combination of attributes that uniquely identifies one and only one instance of an entity. o Foreign key is an attribute relates to another entity in a one-to-one or oneto-many relationship. • Field/Data type (such as Text, Number, Currency, Yes/No, Hyperlink, or Date/Time); indicates the type of data that will be entered into the field. o Text. Character data, also known as text data or string data, can contain any character or symbol not intended for mathematical manipulation. Name and Email are examples of character attributes. o Number. You can use numeric data to perform meaningful arithmetic procedures. o Decimal. A decimal value in a column is rounded down to an integer value. o Date/Time. Date attributes contain calendar dates stored in a special format known as the Julian date format. Field DOB is a date attribute. o Boolean. Logical data can only have true or false (yes or no) values. • Description (an optional description of the field). • Properties (such as the field size and format of the field, any allowable range or required format for the data that will be entered into the field, whether or not the field is required, and any initial value to appear in that field when a new record is added).

2.2 Basic concept of Database 58 Field Name Field/Data Type Field Properties Matric Number Text Length: 50 Name Text Length: 255 Gender ID Text Length: 5 DOB Date/Time Email Text Length: 255 State ID Text Length: 5 Stream ID Text Length: 5 Figure 2.2.1: Data definition for STUDENT table with unique field name. Entity Relationship The basic building blocks of all data models are entities, attributes, and relationships. An entity is a person, place, thing, or event about which data will be collected and stored. It may be physical objects, such as students, lecturers, employees, customers, or products, but entities may also be abstractions, such as college courses, college enrollment, doctor treatments, flight routes or musical concerts. For example, • a STUDENT entity would have many distinguishable student occurrences, such as Muhammad, Fong, and Vijay. • a STREAM entity would have module occurrences, such as Accounting, Biology Science, Physical Science, and Computer Science. • a STATE entity would have state occurrences, such as Kedah, Perlis, Kelantan and Penang. • a GENDER entity would have a fix gender occurrence, such as Male and Female. • a COURSE entity would have course occurrences, such as Computer Science, Physics, Biology and Chemistry. In a file system, entities are the equivalent of file. For example: Student File, Lecturer File, Course File, Enrollment File, Gender File, Module File, State File. An attribute is a characteristic of an entity or object. An attribute has a name and a data type. For example, • A STUDENT entity would be described by attributes such as Matric Number, Name, Gender ID, DOB, Email, State ID, and Stream ID.

2.2 Basic concept of Database 59 • a STREAM entity would be described by attributes such as stream ID and stream name. • a GENDER entity would be described by attributes such as gender ID and gender name. • a STATE entity would be described by attributes such as state ID and state name. • a CUSTOMER entity would be described by attributes such as customer ID, customer name, customer phone number, customer address, and customer credit limit. In a file system, attributes are the equivalent of fields. Example: MATRIC_NO STUDENT_NAME DOB MS2118123456 Muhammad Abdul 01/29/04 12:00 AM MS2218124680 Fong Sai Yuk 02/29/04 10:10 AM MS2218135791 Vijay Thalapathy 11/30/04 08:45 PM MS2218153769 Aminah Amin 12/31/04 11:59 PM MS2218153770 Halimah Halim 01/01/05 12:01 AM A relationship describes an association among entities. Most relationships describe associations between two entities. For example: • A relationship exists between customers and agents that can be described as follows: o an agent can serve many customers, and each customer may be served by one agent. • A relationship between mothers and children. o A mother may give birth to many children, but each child is born by one mother. • A relationship between students and matric card. o a student can only have one matrix card, and one matrix card can only be owned by one student. attributes / fields

2.2 Basic concept of Database 60 The Entity Relationship model uses the term connectivity to label the relationship types. The name of the relationship is usually an active / passive verb. For example: • a PAINTER paints many PAINTINGs / a PAINTINGs painted by a PAINTER. • an EMPLOYEE learns many SKILLs / a SKILLs can be learnt by many EMPLOYEEs • an EMPLOYEE manages a STORE / a STORE is managed by one EMPLOYEE. Entity Relationship Model (ERM) Entity relationship (ER) model (ERM) is a data model that describes relationships (1:1, 1:M, and M:N) among entities at the conceptual level with the help of ER diagrams. The model was developed by Peter Chen. ER models (ERM) are normally represented in an entity relationship diagram (ERD), which uses graphical representations to model database components. Figure 2.2.2 ERD the graphical representation of entities and their relationships in a database structure (Chen notation) • Connectivity is the classification of the relationship between entities. Classifications include 1:1, 1:M, and M:N. • It is used to describe the data model i.e the type of the relationship between entities. o Data models use three types of relationships: one-to-many (Notation: 1:M or 1..*) ENTITY 1 (noun) ENTITY 2 (noun) relationship (verb) 1/M 1/N Connectivities Cardinalities (x1,y1) (x2,y2) Attribute1 Attribute2 Attribute3 Attribute4

2.2 Basic concept of Database 61 many-to-many (Notation: M:N or *..*) one-to-one (Notation: 1:1 or 1..1) • Entity is represented in a rectangular shape. • Attribute is represented in oval shape with label. • Entity relationship is represented in diamond shape with label. • Cardinality is a property that assigns a specific value to connectivity and expresses the range of allowed entity occurrences associated with a single occurrence of the related entity. o It shown on both ends of the relationship line indicates the relations for each entity. o Cardinality expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity. o In the ERD, cardinality is indicated by placing the appropriate numbers beside the entities, using the format (x,y). o The first value represents the minimum number of associated entities, while the second value represents the maximum number of associated entities. The other notation known as Crow’s Foot Crow’s Foot notation is a representation of the entity relationship diagram that uses a three-pronged symbol to represent the “many” sides of the relationship. Drawing Cardinality One Many One (and only one) Zero or one One or many ENTITIY 1 ENTITY 2

2.2 Basic concept of Database 62 Zero or many This section focuses on the following points: • 1:M relationship is the relational modeling ideal. Therefore, this relationship type should be the norm in any relational database design. • 1:1 relationship should be rare in any relational database design. • M:N relationships cannot be implemented as such in the relational model. Later in this section, you will see how any M:N relationship can be changed into two 1:M relationships. The 1:M Relationship A one-to-many relationship is a type of cardinality that refers to the relationship between two entities A and B in which an element of A may be linked to many elements of B, but a member of B is linked to only one element of A. For example, a painter creates many different paintings, but each painting is painted by only one painter. Thus, the painter (the “one”) is related to the paintings (the “many”). Therefore, database designers label the relationship “PAINTER paints PAINTING” as 1:M. Note that entity names are often capitalized as a convention, so they are easily identified. *Crow’s Foot Notation *Chen Notation To read the relationship between PAINTER and PAINTING: • A PAINTER can paint many paintings; • Each PAINTING is painted by one PAINTER PAINTER PAINTING PAINTER paints PAINTING 1 M

2.2 Basic concept of Database 63 Similarly, a customer (the “one”) may generate many invoices, but each invoice (the “many”) is generated by only a single customer. The “CUSTOMER generates INVOICE” relationship would also be labeled 1:M. The 1:M relationship is the norm for relational databases. To see how such a relationship is modeled and implemented, consider the MOTHER and CHILD example shown in Figure 2.2-1. Figure 2.2-1 The 1:M relationship between mother and child To describe the E-R Model: • Each child was born of one and only one mother, but each mother could giving birth to many children. The 1:M relationship is found in any database environment. Students in a typical college or university will discover that each COURSE can generate many CLASSes but that each CLASS refers to only one COURSE. Figure 2.2-2 The 1:M relationship between course and class The 1:M relationship between COURSE and CLASS might be described this way: • Each COURSE can have many CLASSes, but each CLASS references only one COURSE. **Remember to read a 1:M relationship from the “1” side to the “M” side. MOTHER CHILD COURSE CLASS CUSTOMER INVOICE

2.2 Basic concept of Database 64 The 1:1 Relationship A one-to-one relationship is a type of cardinality that refers to the relationship between two entities A and B in which one element of A may only be linked to one element of B, and vice versa. Here, a country has only one capital city, and a capital city is the capital of only one country. As the 1:1 label implies, one entity in a 1:1 relationship can be related to only one other entity, and vice versa. For example, one faculty leader, a dean can lead only one faculty, and one faculty can have only one department leader (dean). The entities DEAN and FACULTY thus exhibit a 1:1 relationship. The basic 1:1 relationship is modeled in Figure 2.2-3. *Crow’s Foot Notation Figure 2.2-3 The 1:1 relationship between dean and faculty *Chen Notation DEAN FACULTY DEAN lead FACULTY 1 1 COUNTRY CAPITAL CITY

2.2 Basic concept of Database 65 A retail company’s management structure may require that each of its stores be managed by a single employee. In turn, each store manager, who is an employee, manages only a single store. Therefore, the relationship “EMPLOYEE manages STORE” is labeled 1:1. *Crow’s Foot Notation Figure 2.2-4 The 1:1 relationship between professor and department *Chen Notation To read the One-to-One (1:1) relationship between EMPLOYEE and STORE: • an EMPLOYEE manages one STORE; • each STORE is managed by one EMPLOYEE. EMPLOYEE STORE EMPLOYEE manages STORE 1 1

2.2 Basic concept of Database 66 The M:N Relationship A many-to-many relationship is a type of cardinality that refers to the relationship between two entities, say, A and B, where A may contain a parent instance for which there are many children in B and vice versa. For example, the relationship “AUTHOR writes BOOK”. An AUTHOR can write several BOOKs, and a BOOK can be written by several AUTHORs An employee may learn many job skills, and each job skill may be learned by many employees. Database designers label the relationship “EMPLOYEE learns JOB SKILL” as M:N. Similarly, a student can take many classes and each class can be taken by many students, thus yielding the M:N label for the relationship expressed by “STUDENT takes CLASS.” To explore the many-to-many relationship, consider a typical college environment. The ER model in below figure shows this M:N relationship. *Crow’s Foot Notation STUDENT SUBJECT AUTHOR BOOK EMPLOYEE JOB SKILLS

2.2 Basic concept of Database 67 *Chen Notation Note the features of the ERM in above figure: To read the Many-to-Many (M:N) relationship between SUBJECT and STUDENT: • Each SUBJECT can have many STUDENTs; • each STUDENT can take many SUBJECTs. A Many-to-Many Relationship: *Crow’s Foot Notation *Chen Notation To read the Many-to-Many (M:N) relationship between EMPLOYEE and STORE: • an EMPLOYEE can learn many skills; • each skill can be learned by many EMPLOYEES STUDENT takes SUBJECT M N EMPLOYEE SKILLS EMPLOYEE learns SKILLS M N

2.2 Basic concept of Database 68 Cardinalities Previously you learned that entity relationships may be classified as one-to-one, one-tomany, or many-to-many. You also learned how such relationships were depicted in the Chen and Crow’s Foot notations. *Crow’s Foot Notation *Chen Notation • Cardinality is a property that assigns a specific value to connectivity and expresses the range of allowed entity occurrences associated with a single occurrence of the related entity. It represents the number of occurrences in the related entity. • For example, o The cardinality (1,1) next to the LECTURER entity in the “LECTURER teaches CLASS” relationship indicates that each (1) class is taught by one and only one (1) lecturer, That is, each CLASS entity occurrence is associated with one and only one entity occurrence in LECTURER. o Similarly, the cardinality (1,4) next to the CLASS entity indicates that Each (1) lecturer teaches up to four (4) classes, LECTURER CLASS Cardinalities (1,1) (1,4) LECTURER teach CLASS 1 M (1,1) (1,4) Cardinalities

2.2 Basic concept of Database 69 which means that the LECTURER table’s primary key value occurs at least once and no more than four times as foreign key values in the CLASS table. o If the cardinality had been written as (1,N), there would be no upper limit to the number of classes a lecturer might teach. 2.2.2 Representations of a Relational Database (T2C1) Characteristics of a Relational Table • A table is perceived as a two-dimensional structure composed of rows and columns. • Each table row (tuple) represents a single entity occurrence (record) within the entity set. • Each table column has a distinct name, and represents an attribute / field name. MATRIC_NO STUDENT_NAME DOB MS2118123456 Muhammad Abdul 01/29/04 12:00 AM MS2218124680 Fong Sai Yuk 02/29/04 10:10 AM MS2218135791 Vijay Thalapathy 11/30/04 08:45 PM MS2218153769 Aminah Amin 12/31/04 11:59 PM • Each intersection of a row and column represents a single data value. attributes with distinct name records Columns Rows

2.2 Basic concept of Database 70 • All values in a column must conform to the same data type such as Text, Number (Integer, Double), Yes/No, or Date/Time. Field Name Field Type Description Matric Number Text Matric No. Name Text Name of the student DOB Date/Time Date of birth (mm/dd/yy hh:mm AM/PM) • Each column has a specific range of values known as the attribute domain. • The order of the rows and columns is not important to the DBMS. • Each table must have an attribute or combination of attributes that uniquely identifies each row. 2.2.3 Data Integrity (T1C2) Data integrity is a condition in which the data in the database complies with all entity and referential integrity constraints. Data integrity ensures the consistency of data. Data that displays data inconsistency is also referred to as data that lacks data integrity. Data integrity is defined as the condition in which all of the data in the database is consistent with the real-world events and conditions. In other words, data integrity means that: • Data is accurate – there are no data inconsistencies. • Data is verifiable – the data will always yield consistent results. 2.2.4 Database Object (T1C2) Databases are composed of many objects but the following are the four (4) major objects: • Tables • Queries • Forms • Reports Table • Table is an object that is used to define and store data. When you create a new table, Access asks you to define fields which is also known as column headings. Data type

2.2 Basic concept of Database 71 • Each field must have a unique name, and data type. • Tables contain fields or columns that store different kinds of data, such as a name or an address, and records or rows that collect all the information about a particular instance of the subject, such as all the information about a customer or employee etc. • You can define a primary key, one or more fields that have a unique value for each record, and one or more indexes on each table to help retrieve your data more quickly. Query • Most DBMSs include query by example (QBE), a feature that has a graphical user interface to assist users with retrieving data. • An object that provides a custom view of data from one or more tables. Queries are a way of searching for and compiling data from one or more tables. • Running a query is like asking a detailed question of your database. • When you build a query in Access, you are defining specific search conditions to find exactly the data you want. • In Access, you can use the graphical query by example facility or you can write Structured Query Language (SQL) statements to create your queries. • You can define queries to Select, Update, Insert, or Delete data. • You can also define queries that create new tables from data in one or more existing tables. Form • A form, sometimes called a data entry form, is a window on the screen that provides areas for entering or modifying data in a database. You use forms to retrieve and maintain the data in a database. To reduce data entry errors, well-designed forms should validate data as it is entered. • Form is an object in a desktop database designed primarily for data input or display or for control of application execution. You use forms to customize the presentation of data that your application extracts from queries or tables.

2.2 Basic concept of Database 72 • Forms are used for entering, modifying, and viewing records. • The reason forms are used so often is that they are an easy way to guide people toward entering data correctly. • When you enter information into a form in Access, the data goes exactly where the database designer wants it to go in one or more related tables. Report • A report writer, also called a report generator, allows users to design a report on the screen, retrieve data into the report design, and then display or print the report. Unlike a form, you use a report writer only to retrieve data. Report writers usually allow you to format page numbers and dates; titles and column headings; subtotals and totals; and fonts, font sizes, color, and shading; and to include images. Some report writers allow you to create a report as a webpage. • Report is an object in desktop databases designed for formatting, calculating, printing, and summarizing selected data. • You can view a report on your screen before you print it. • If forms are for input purposes, then reports are for output. • Anything you plan to print deserves a report, whether it is a list of names and addresses, a financial summary for a period, or a set of mailing labels. • Reports are useful because they allow you to present components of your database in an easy-to-read format. • You can even customize a report's appearance to make it visually appealing. • Access offers you the ability to create a report from any table or query.

2.2 Basic concept of Database 73 Exercise 2.2 Basic concept of Database 1 Define the basic concepts of database. (a) Data hierarchy: the systematic organization of data, often in a hierarchical form. (b) Bit: the smallest unit of data the computer can process. (c) Byte: eight (8) bits grouped together in a unit. (d) Character: represented by one (1) byte. (e) Entity: a person, place, thing, or event about which data will be collected and stored. (f) Attribute: a characteristic of an entity or object. An attribute has a name and a data type. (g) Primary key: fields that have a unique value for each record. (h) Foreign key: a field in a table that relates to another table. (i) Relationship: an association among entities. (j) Entity relationship model: a data model that describes relationships among entities. (k) Connectivity: the type of the relationship between entities. (l) Cardinality: represent the number of occurrences in the related entity. (m) 1:M relationship: a type of cardinality that refers to the relationship between two entities A and B in which an element of A may be linked to many elements of B, but a member of B is linked to only one element of A. (n) 1:1 relationship: a type of cardinality that refers to the relationship between two entities A and B in which one element of A may only be linked to one element of B, and vice versa. (o) M:N relationship: a type of cardinality that refers to the relationship between two entities, say, A and B, where A may contain a parent instance for which there are many children in B and vice versa. 2 Describe the representations of a relational database (a) Field a combination of one or more related characters or bytes. (b) Record groups of related fields. (c) Table / File made up of related records.

2.2 Basic concept of Database 74 3 A hospital manages patients’ record by controlling access for deletion and addition of records and allows searching for patients’ record. (a) Identify the best approach to manage patients’ record. Justify your answer. (b) Suggest the tool that enables the hospital to manage patients’ information. (c) Explain the difficulties of managing patient data using file systems. 4 The following are purchasing order database scheme of RIMAU Pte. Ltd. ORDER ORDER_ITEM PRODUCT VENDOR OrderID OrderID ProductID VendorID OrderDate ProductID ProductName VendorName QuantityOrdered ExpiryDate ContactNo Price Address VendorID Based on the database scheme above, answer the following questions: (a) Give the most appropriate data type for VendorName field. Justify your answer. (b) Identify the most appropriate field to be chosen as a primary key in table ORDER, ORDER_ITEM, PRODUCT and VENDOR. (c) Identify a table that contains a foreign key. Justify your answer. 5 Given the file structure shown in Figure below, answer Problems (a) – (d). (a) What is the most suitable name for the table? (b) How many fields? Name all the fields. (c) How many records? Write one (1) example of the record. (d) Which field is the most suitable as primary key?

2.2 Basic concept of Database 75 6 Write the relationship and connectivity between these entities. ENTITY1 RELATIONSHIP CONNECTIVITY ENTIITY2 DEPARTMENT operates 1:M UNIT UNIT has 1:M STUDENT UNIT employs 1:M LECTURER UNIT offers 1:M COURSE COURSE generates 1:M CLASS SEMESTER includes 1:M CLASS LECTURER is head of 1:1 DEPARTMENT LECTURER chairs 1:1 UNIT LECTURER teaches 1:M CLASS LECTURER advises 1:M STUDENT STUDENT has 1:1 IC STUDENT has M:1 GENDER STUDENT enrols in M:N CLASS BUILDING contains 1:M ROOM ROOM is used for 1:M CLASS 7 Palara Holdings is a construction company situated in Kuala Nerang, Kedah. It has many branches nationwide and each branch consists of several departments. Total employees are more than one thousand. The company intends to have their own database that will assist them in managing staff information. Based on the situation above: (a) Identify all entities/tables involved. (b) List possible attributes/fields for each entity identified in 6(a). (c) Draw the possible Entity Relationship Diagrams for the case above.

2.2 Basic concept of Database 76 8 Based on figure below, answer the following questions. (a) Write the business rule(s) that govern the relationship between AGENT and CUSTOMER. (b) Given the business rule(s) you wrote in (a), create the basic Crow’s Foot ERD. 9 Draw a single ER diagram for the following rules, showing Entities, Relationships and Cardinality. (a) An author can write many books. A book may be written by many authors. (b) A football team consists of many players. A player plays for only one football team. (c) A doctor writes one or more prescriptions. A prescription can be issued by only one doctor. (d) A department has many employees. An employee works in only one department. (e) A mother may has many children. A child has one mother. (f) Each student attends several classes. There are several students in each class. 10 Create an ERD for each of the following description: (a) A lecturer teaches zero, one or many classes and a class is taught by one lecturer. (b) A course may generate zero, ONE or MANY classes and a class comes from one course. (c) A class is held in one room but a room has many classes. (d) Combine all the ER diagram in (a), (b) and (c) into a single ER Diagram.

2.2 Basic concept of Database 77 11 Explain the concept of data integrity. 12 There are four (4) objects in a database. Give one (1) function for each database object. 13 Answer the following based on RIMAU Pte. Ltd. database system above in question 4: (a) Suggest an appropriate database object use when the manager of RIMA Sdn Bhd wants specific data. Justify your answer. (b) RIMA Sdn Bhd. management wants you to assist the marketing manager to place order. Explain how FORM can assist the manager. (c) Explain how the output from REPORT can help RIMA Sdn. Bhd. manager.

Written Assignment 78 WRITTEN ASSIGNMENT Suppose you are required to design a relational database system for hospital management system. Step 1: Determine business rules (used to define entities, attributes, and relationships) • A doctor may treat many patient. • A patient is treated by only one doctor. This business rules establish two entities (DOCTOR and PATIENT) and a 1:M relationship between those two entities. Entity Doctor has key attribute (Primary key), Doctor_id which will be used to identify the doctors. Entity Patient has many attributes Patient_id, Name, Doctor_id, DOB, Age, etc. DOCTOR Doctor_id Name Dept_id PATIENT Patient_id Name Doctor_id

Written Assignment 79 The Doctor and Patient entity have a one-to-many (1:M) relationship as a Doctor may treat more than one patient. Step 2: Translate business rule to ERM. A One-to-Many (1:M) relationship: • a DOCTOR can treat many PATIENTs; • each PATIENT is treated by one DOCTOR. treats 1 M treats 1 M DOCTOR Doctor_id Name Dept_id PATIENT Patient_id Name Doctor_id

Written Assignment 80 Step 3: The ERM in Relational Database Data Dictionary Field Name Field/Data Type Field Properties Doctor_id Text Length: 20 Name Text Length: 255 Dept_id Number Length: 2 Field Name Field/Data Type Field Properties Patient_id Text Length: 20 Name Text Length: 255 Doctor_id Text Length: 20 Data definition for DOCTOR table with unique field name. Data definition for PATIENT table with unique field name. Table name: DOCTOR Field name: Doctor_id, Name, Dept_id Primary key: Doctor_id Foreign key: None Doctor_id Name Dept_id UD41 Mohamad Anuar Mohamad G01 UD44 Amin M. Sani H04 UD48 Ismail Yaacob G01 UD52 Kang Bean Chong Z99 UD54 Minder Singh X76 Table name: PATIENT Field name: Patient_id, Name, Doctor_id Primary key: Patient_id Foreign key: Doctor_id Patient_id Name Doctor_id P001 Muhammad Abdul UD54 P002 Fong Sai Yuk UD48 P003 Vijay Thalapathy UD41 P004 Halimah Halim UD48

DC014 COMPUTER SCIENCE | ASSIGNMENT RUBRIC 8 Item Weight Excellent (Mark = 3) Good (Mark =2) Database File Create file, save in a specific location & file is retrievable 1 Able to provide all THREE following tasks: ֊ Create new file in a specific location ֊ Correct file name ֊ Retrieve file Able to provide TWO of the following tasks: ֊ Create new file in a specific location ֊ Correct file name ֊ Retrieve file Data Hierarchy Data, field & record are correctly identified 1 Able to identify all THREE items correctly: ֊ Data ֊ Field ֊ Record Able to identify TWO of the three following items correctly: ֊ Data ֊ Field ֊ Record Entity Relationship Entities relationships and cardinalities are correctly defined 1 Able to define all THREE items correctly: ֊ Entities ֊ Relationships ֊ Cardinalities Able to define TWO of the following items correctly: ֊ Entities ֊ Relationships ֊ Cardinalities

1 Attachment 1 Marginal (Mark = 1) Unacceptable (Mark = 0) Points (Weight x Mark) Examiner Moderat or Able to provide ONE of the following tasks: ֊ Create new file in a specific location ֊ Correct file name ֊ Retrieve file Unable to provide any of the following tasks: ֊ Create new file in a specific location ֊ Correct file name ֊ Retrieve file ֊ Able to identify ONE of the three following items correctly: ֊ Data ֊ Field ֊ Record Unable to identify any of the following items correctly: ֊ Data ֊ Field ֊ Record ֊ Able to define ONE of the following items correctly: ֊ Entities ֊ Relationships ֊ Cardinalities Unable to define any of the items correctly: ֊ Entities ֊ Relationships ֊ Cardinalities ֊

DC014 COMPUTER SCIENCE | ASSIGNMENT RUBRIC 8 Data Type Data type are correctly identified 1 Able to identify all FIVE items correctly: ֊ Text ֊ Number ֊ Decimal ֊ Date/Time ֊ Boolean Able to identify FOUR of the five following items correctly: ֊ Text ֊ Number ֊ Decimal ֊ Date/Time ֊ Boolean Data dictionary Table name, field name, primary key & foreign key are correctly identified 2 Able to identify all FIVE items correctly: ֊ Table name ֊ Field name ֊ Primary key ֊ Foreign key Able to identify FOUR of the five following items correctly: - Table name - Field name - Primary key - Foreign key Data Modeling Entity relationship model (crow's foot or chen notations and symbols) are appropriately design 2 Able to draw ALL the following symbol and notations correctly: 1. Crow’s foot diagram: - Entity is represented in a rectangular - Attributes written clearly - Relationships between entities clearly connected - Cardinality shown on both ends of the relationship line Able to draw TWO or more symbol and notations correctly: 1. Crow’s foot diagram : - Entity is represented in a rectangular - Attributes written clearly - Relationships between entities clearly connected - Cardinality shown on both ends of the relationship line

2 Attachment 1 Able to identify TWO of the five following items correctly: ֊ Text ֊ Number ֊ Decimal ֊ Date/Time ֊ Boolean Unable to identify any of the following items correctly: ֊ Text ֊ Number ֊ Decimal ֊ Date/Time ֊ Boolean ֊ Able to identify TWO of the five following items correctly: ֊ Table name ֊ Field name ֊ Primary key ֊ Foreign key Unable to identify any of the following items correctly: ֊ Table name ֊ Field name ֊ Primary key ֊ Foreign key ֊ Able to draw ONE of the following symbol and notations correctly: 1. Crow’s foot diagram: - Entity is represented in a rectangular - Attributes written clearly - Relationships between entities clearly connected - Cardinality shown on both ends of the relationship line Unable to draw any relationship model.

DC014 COMPUTER SCIENCE | ASSIGNMENT RUBRIC 8 indicates how the entities relate to each other. Or 2. Chen notation diagram: - Entity is represented in a rectangular - Attribute is represented in oval with label - Entity relationship is represented in diamond shape with label - Cardinality shown on both ends of the relationship line indicates the relations for each entity indicates how the entities relate to each other. Or 2. Chen notation diagram: - Entity is represented in a rectangular - Attribute is represented in oval with label - Entity relationship is represented in diamond shape with label - Cardinality shown on both ends of the relationship line indicates the relations for each entity Written Format Documentation includes all the requirements 1 Able to provide all THREE following items: - Cover page contains the lecturer's & student’s details. - Table of content - Apply all of text formatting (page number, spacing, font size, margin neatly apply) Able to provide TWO of the three following items: - Cover page contains the lecturer's & student’s details. - Table of content - Apply most of text formatting (page number, spacing, font size, margin neatly apply)

3 Attachment 1 indicates how the entities relate to each other. Or 2. Chen notation diagram: - Entity is represented in a rectangular - Attribute is represented in oval with label - Entity relationship is represented in diamond shape with label - Cardinality shown on both ends of the relationship line indicates the relations for each entity Able to provide ONE of the three following items: - Cover page contains the lecturer's & student’s details. - Table of content - Apply some of text formatting (page number, spacing, font size, margin neatly apply) Unable to provide any of the following items: - Cover page contains the lecturer's & student’s details. - Table of content - Apply least text formatting (page number, spacing, font size, margin neatly apply)

DC014 COMPUTER SCIENCE | ASSIGNMENT RUBRIC 8 Submission Assignment submitted within the time frame 1 Assignment is submitted within a time frame. Assignment is submitted late but still on the same day/date Total Marks *Rubric was adapted from Totaro and Guidry, 2020 Reference Totaro, M. W., & Guidry, B. N. (2013). The advanced database course and learning. International Journal of Information and Operations Management

4 Attachment 1 Assignment is submitted ONE day late Assignment is submitted TWO days late or onwards 30 30 10 10 the information systems 2010 model curriculum: an experiential approach to Education, 5(2), 115-129.

3.1 What is Network? 85 Topic 3: Network & Internet Technology 3.1 What is Network? Learning Outcomes: At the of this lesson, students should be able to: (a) Define network. (b) Describe several uses of network. (c) Name types of networking media. (d) Describe wired and wireless networking media. (e) State network device. (f) Describe the function of each network device. 3.1.1 Network (T1C1) A network is a collection of computers and other hardware devices connected together so that network users can share hardware, software, and data, as well as communicate with each other electronically. Computers and other hardware devices refers to computers, smart phones, tablets, printers, scanners, ATM machines, and kiosks. Today, computer networks are converging with telephone networks and other communications networks, with both data and voice being sent over these networks. Computer networks range from small private networks to the Internet and are widely used by individuals and businesses today. 3.1.2 Uses of Network / Networking Applications (T2C2) Common uses of networking applications include: • The Internet • Telephone Service • Television and Radio Broadcasting • Global Positioning System (GPS) Applications • Monitoring Systems • Multimedia Networking • Videoconferencing, Collaborative Computing and Telecommuting • Telemedicine

3.1 What is Network? 86 3.1.2.1 The Internet The Internet is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. The Internet is the largest computer network in the world. Many networking applications today (such as information retrieval, shopping, entertainment, and e-mail) take place via the Internet. Accessing Web pages While the term Internet refers to the physical structure of that network, the World Wide Web (WWW) refers to one resource—a collection of documents called Web pages— available through the Internet. A group of Web pages belonging to one individual or company is called a Web site. Web pages are stored on computers (called Web servers) that are continually connected to the Internet; they can be accessed at any time by anyone with a computer and an Internet connection. Web pages are viewed using a Web browser, such as Internet Explorer (IE), Chrome, Safari, Opera, or Firefox. Exchanging e-mail messages Electronic mail (more commonly called e-mail) is the process of exchanging electronic messages between computers over a network—usually the Internet. You can send an e-mail message from any Internet-enabled device (such as a personal computer or mobile device) to anyone who has an Internet e-mail address. Other Internet-based Activities This section will be discussed later in subtopic 3.2.2 Web Activities. 3.1.2.2 Telephone Service Telephone Service is a voice-grade telephone service employing analog signal transmission over copper loops.

3.1 What is Network? 87 The original telephone network called the plain old telephone service (POTS), was one of the first communications networks. This network is still used today to provide telephone service to conventional landline phones, and is used for some types of Internet connections. Mobile phones are phones that use a wireless network for communications instead of the regular telephone network. The most common type of mobile phone is the cellular (cell) phone, which communicates via cellular technology. Another type of mobile phone is the satellite phone, which communicates via satellite technology. An emerging option is the cellular/satellite dual-mode phone that can be used with cellular service when it is available and then switches to satellite service when cellular service is not available. 3.1.2.3 Television and Radio Broadcasting Television broadcasting is a telecommunications network for distribution of television program content, where a central operation provides programming to many television stations providers. Radio broadcasting is transmission of audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. These original communications networks are still used to deliver TV and radio content to the public, though some of this content is also available via the Internet today. Other networks involved with television content delivery are • cable TV networks, • satellite TV networks, and • the private closed-circuit television (CCTV) systems used by businesses for surveillance and security purposes. Cable and satellite TV networks are also used today to provide access to the Internet.

3.1 What is Network? 88 3.1.2.4 Global Positioning System (GPS) Applications GPS is a satellite navigation system used to determine the ground position of an object. A GPS receiver measures the distance between the receiver and four GPS satellites simultaneously to determine the receiver’s exact geographic location; these receivers are accurate to within 3 meters. GPS receivers are commonly used • by individuals to determine their geographic location while hiking and to obtain driving directions while traveling. • on the job, such as by surveyors, farmers, fishermen, and public safety personnel. • to guide vehicles and equipment (for example, to locate and dispatch ambulances, police cars, and other emergency vehicles, or to guide bulldozers and other construction equipment automatically using that device’s preprogrammed instructions). • to guide munitions and trucks, as well as to track military aircraft, ships, and submarines Most smartphones today include GPS capabilities, which allow the use of location-specific services and applications such as using your location in Web searches, social media activities, and self-guided tours. GPS capabilities are also built into consumer devices that are designed for specific purposes, such as fitness devices that use GPS technology to record workout data for runners or bicyclists.

3.1 What is Network? 89 3.1.2.5 Monitoring Systems Monitoring systems is a networking technology to determine the current location or status of an object. Some monitoring systems in use today use the RFID tags and RFID readers to monitor the status of the objects (such as shipping boxes, livestock, or expensive equipment) to which the RFID tags are attached. Other monitoring systems use GPS technology. For instance, • many law enforcement ankle bracelet monitoring systems use GPS to detect if the offender has left his or her authorized areas, and • the OnStar system built into many GM cars uses GPS to locate vehicles when the occupant activates the service or when sensors indicate that the car was involved in an accident. There are also vehicle monitoring systems that are installed in cars by parents and employers to monitor the location and use of the vehicles (by children or employees, respectively) using networking technology; • Child monitoring systems allow parents to monitor the physical locations of their children. • Both types of monitoring systems typically record a location history; many also allow the location of a vehicle or child to be tracked in real time via a Web site or mobile app. • GPS systems are also designed to be used to track elderly parents or by individuals who are hiking or traveling so they can be located if they become lost or injured. Monitoring system for home healthcare Electronic medical monitors take the vital signs of an individual (such as weight, bloodsugar readings, or blood pressure) or prompt an individual to answer questions (such as if he or she has eaten yet that day or has taken prescribed medication). These monitors then transfer readings or the individual’s responses to a healthcare provider via the Internet or a telephone network for evaluation and feedback and to detect potential problems as early as possible. Other monitoring systems use sensors—devices that respond to a stimulus (such as heat, light, or pressure) and generate an electrical signal that can be measured or interpreted.

3.1 What is Network? 90 The sensors are usually small and lightweight; contain the necessary hardware and software to sense and record the appropriate data, as well as transmit the data to other devices in the network; and include a power source (typically a battery). 3.1.2.6 Multimedia Networking Multimedia network is a network application to deliver digital multimedia content to computers. Home networks are also used to connect smart TVs to the Internet. A multimedia networking device (a digital media receiver or digital media streamer) can be used to connect a conventional television to your home network to deliver content from your networked devices or the Internet to that television. Other multimedia networking devices are designed to placeshift multimedia content; that is, to allow individuals to view their multimedia content at a more convenient location. 3.1.2.7 Videoconferencing, Collaborative Computing and Telecommuting Videoconferencing is the two-way or multipoint reception and transmission of audio and video signals by people in different locations for real time communication. Videoconferencing is the use of networking technology to conduct real-time, face-to-face meetings between individuals physically located in different places. Videoconferencing can take place between individuals using their personal computers and the Internet or it can take place using two mobile phones or other mobile devices with videoconferencing capabilities. Larger business videoconferences often take place via a dedicated videoconferencing setup using telepresence videoconferencing, which more closely mimics a real-time meeting environment. Although telepresence videoconferencing setups are expensive, with travel becoming increasingly more expensive and time consuming, many businesses view videoconferencing as a viable replacement for face-to-face meetings. Collaborative computing is a networking technology with collaborative software tools to enable individuals to work together on documents and other project components. Some

3.1 What is Network? 91 collaboration software also includes shared calendars, project scheduling, and videoconferencing tools. With telecommuting, individuals work from a remote location (typically their home) and communicate with their place of business and clients via networking technologies. Telecommuting • allows the employee to be flexible, such as to work nontraditional hours or remain with the company after a relocation. • enables a company to save on office and parking space, as well as office-related expenses such as utilities. • helps cut down on the traffic and pollution caused by traditional work commuting. • gives a business the possibility to continue operations during situations that may affect an employee’s ability to get to the office, such as o during hurricanes, o during a bridge or highway closure, or o during a flu outbreak.