Name: OsikoyaOmotoyosi Samuel Project: The Database Accessor: HashimShaheen Level: HND ComputingWhat is a Database? The database is a very broad topic and has various definitions but basically has onemeaning. Oracle Corporation defines a database as a collection of physical files that are managedby an instance of their database software product where a file is a collection of related records thatare stored as a single unit by an operating system. Microsoft SQL and Sybase defines a database asa collection of data pieces that have a common owner. One may get confused when working withdifferent products, for example, the definition given by Microsoft for a database is exactly howOracle defines a Schema. A database is a shared, integrated computer structure that stores a collection of End-userdata, that is, raw facts of interest to the end user AND metadata, (or data about data) through whichthe end-user data are integrated and managed. Simply put, DB, as database is often called orrepresented, is an assembly of any information in an organized manner, such that a computerprogram or a person can easily access pieces of data depending on what is being searched for orneeded.We can also say thatthe database consists of files and files are made up of records whichconsists of data pieces The metadata is a description of the data characteristics and the set of relationships that linksthe data found within the database. For example, the metadata component stores information suchas the name of each data element, the type of values (numeric, dates, or text) stored on each dataelement, whether or not the data element can be left empty, and so on. The metadata also provideinformation that complements and expands the value and use of the data.Summarily, the metadata present a more complete picture of the data in the database. Due to the importance of data and then, the database, it is expedient to put things in thehands of an expert, a Database Specialist, who is specialized in the field. A database specialist controls and manages the software program for a company. This is theperson responsible for the collection and management of typical information on prospects andcustomers of business in a given organization. While the database specialist manages the data thatgoes into the software program, the manager also works with various other employees in thecompany to collect, monitor and share the information that is collected.
The first thing that a database specialist does when working for an employer or a client is to knowwhat the client wants or needs. Databases are used across all types of industries, but each businessor company has its own different needs and requirements because of the different works they do.Once the database specialist knows what a company or organization wants, the database specialistcan evaluate the current software.Analyzing the current database software allows the database specialist to determine if the companyis collecting the right or wrong information from customers. For some companies, it may becollecting information such as the name and mailing address of the customer, along with a phonenumber, email address and a record of the customer’s buying behaviour with the company.The database specialist will now use this information to report findings to different departmentswithin the company. For example, a database specialist typically can run reports from the software.These reports can help the marketing department of the company determine how marketingcampaigns affect customer buying behaviour. The marketing department also uses the informationthat the database specialist collects to send out marketing materials, including emails, brochures,direct mail campaigns, coupons, catalogs and more.The specialist also spends a lot of time updating the information that is in the software. Forexample, if the marketing department sends out a postcard to the entire database that includes acoupon code, the data specialist will work with the sales people who are taking the orders onlineand via telephone to track the response to the direct mail campaign.The database specialist will also receive postcards that get returned as undeliverable for variousreasons. The specialist then contact the customer in an attempt to update their contact information inthe system or remove any of the information that is not accurate. If the postcard gets returned with anew address, but the post office is unable to forward it because the forwarding has expired, then thedatabase specialist can put the new address in the database.What a database looks like:Showing a database of customer information in a particular company Name Age Address Email Phone Number Date of Last business with customer Mrs. Jaden 65 2 Smith001@linuxmail.org +120235799764 11-12- Smith Montgomery 2012 road, Alaska, USA Mrs. Goldie 42 Plot 24b G_phillip@yahoo.com +447877474749 20-02- phillip green way, 2013 hatfield, England Mr. Samuel 19 2, Nimrod Robby@gmail.com Not Provided 3-03- Roberto Drive, 2013 Nairobi, Kenya
Miss. 24 23, T.Balogun@rocketmail.com +2348035175111 TundeBalogun Adedoyin Street, Ogba, Lagos, Nigeria Mr. Patrick 51 23, Roe Patjose@yahoo.com +4474678373932 15-03- Jose Green lane, 2011 Hatfield, EnglandShowing the User interface of a Database system New Customer? Register your Details correctly. Fields marked with (*)MUSTbe filled. Surname: Middle Initial: Date of Birth: dd mm yyyy First Name: Address: Email: Phone Number: Have an account already? Sign in here HOW DATABASES WORK ACROSS ORGANIZATIONSRole of the Database in an Organization An organization is traditionally viewed as a three level pyramid-operational activities at thebottom, management planning and control activities in the middle and strategic planning and policymaking in top management. The corporate database contains data relating to the organization, itsoperations, its plan and its environment.
State of Database Management in Organizations The needs of organizations and management are changeable, diverse and often ill-defined,yet they must be met. Added to these are outside pressures from federal taxing authorities, federalsecurities agencies and legislators making privacy laws. Both internal and external forces demandthat organizations exercise control over their data resources. Decisions and actions in the organization are based upon the image contained in thecorporate database. Managerial decisions direct the actions at the operational level and produceplans and expectations which are formally captured and stored in the corporate database.Transactions record actual results of organizational activities and environmental changes and updatethe database to maintain a current image. Basically, People in the organization query the database for information to conduct the dailyoperations. Middle management receives reports comparing actual results to previously recordedplans and expectations. The corporate database provides data for modeling and forecasting whichsupport top management needs. The corporate database supports all levels of an organization and isvital for operations, decision making and the management process. While management seeks to control data resources, computer applications grow. When acorporation achieves comprehensive support of its operations, for instance, computer applicationsbegin to penetrate into higher management levels. With comprehensive database support ofoperations, an MIS can mature as a tool for planning, control and decision making. Earlier, in thedevelopment of an MIS, an organization must appoint a DBA to manage its data resources. While an organization’s move toward the database approach can be hastened by theacquisition of a DBMS, the latter is not necessary. Most commercially available DBMS’s fallsubstantially short of ideal capabilities, making their acquisition an interim measure - a move tohelp the organization learn how to operate in a managed data environment. In seeking DBMScapability, building one’s own system is unrealistic except for large organizations with specialneeds, such as a very large database or large volumes of known transactions requiring rapid onlineresponse. Data is a vital resource in an organization and must be managed. The organizationaldatabase is an essential component in a management information system. Of the four components ofa data processing system, attention to data has lagged behind the development of machines andprogramming technology. Taking a database approach requires an organization to focus on data as avalued resource. Data is separate from programs and application systems which use it.
Typical database applications include: Banking: all transactions Airlines: reservations, schedules Universities: registration, grades Sales: customers, products, purchases Online retailers: order tracking, customized recommendations Manufacturing: production, inventory, orders, supply chain Human resources: employee records, salaries, tax deductions etc.Every day, everybody makes use of data, hence the need for database. From small scale businessesto large corporation, to individuals etc., the importance of data and database cannot be be-littled.But what is data? Data can be defined as raw facts. The term raw implies that the data has not been processedor worked upon to give implied meaning. For example, the digits 2344223783 is a raw fact, as it hasnot been worked upon to give any implied meaning. After processing by respective end-users, itcould mean so many things. It could be some amount of money been stored away in a bank, henceits a calculated Currency to that user, with its unit as the currency of the country. It could be asocial security number SSN, of a US citizen. It could be the number of citizens living in a particularcountry, at a particular time, hence its a demographic figure, and so on. Such processed raw facts ordata is called Information. Information is the result of processing raw data to reveal its meaning. Data processing canbe as simple as organizing data to reveal patterns or as complex as making forecasts or drawinginferences using statistical modeling. To reveal meaning, information requires context. For example,an average temperature reading of 105 degrees does not mean much unless you also know itscontext: Is this in degrees Fahrenheit or Celsius? Is this a machine temperature, a body temperature,or an outside air temperature? It should be noted that raw data must be properly formatted for storage, processing, andpresentation. As it is,Timely and useful information requires accurate data. Such data must be properlygenerated and stored in a format that is easy to access and process. And, like any basic resource, thedata environment must be managed carefully. Hence, Data management is a discipline that focuses on the proper generation, storage, andretrieval of data. Given the crucial role that data play, it is seen that data management is a coreactivity for any business, government agency, service organization, or charity. But efficient datamanagement typically requires the use of a computer database which is usually operated by adatabase administrator.DATABASE ADMINISTRATOR
This is a person who handles the environmental aspect of a database. He/she is the personwho has complete control on the database.Roles of a Database Administrator The database administrator performs a critical role within an organization and is animportant and key role in Database Management Systems. The major responsibility of a databaseadministrator is to handle the process of developing the database and maintaining the database of anorganization. The database administrator is responsible for defining the internal layout of thedatabase and ensuring the internal layout optimizes system performance. The database administrator has full access over all type of important data of an organization.The database administrator decides what data will be stored in the database and how to organizedata in database so that it can be access easily on requirement or need of an organization. To designthe database of an organization, the database administrator must have a meeting with users anddetermine their requirements. The database administrator is also responsible for preparing documentation, includingrecording the procedures, standards, guidelines, and data descriptions necessary for the efficient andcontinuing use of the database environment. Documents should include materials to help end users,database application programmers, the operation staff, and all personnel connected with thedatabase management system. The database administrator is responsible for monitoring the database environment, such asseeing that the database is meeting performance standards, making sure the accuracy, integrity, andsecurity of data are maintained. The database administrator is also responsible to manage any enhancements into thedatabase environment.Other roles of Data Administrator may include: (a) Establishing the needs of users and monitoring user access and security; (b) Monitoring performance and managing parameters to provide fast query responses to front end users; (c) Mapping out the conceptual design for a planned database in outline; (d) Considering both back end organization of data and front end accessibility for end users and; (e) Refining the logical design so that it can be translated into a specific data model and more.ORGANIZATIONAL ISSUES In the heart of the matter some issues that affects the use of database within an organization.A database security manager is the most important asset to maintaining and securing sensitive datawithin an organization. Database security managers are required to multitask and juggle a variety of
headaches that accompany the maintenance of a secure database.If you own a business it is important to understand some of the security problems that occur withinan organization and how to avoid them. If you understand the how, where, and why of databasesecurity you can prevent future problems from occurring.Daily Maintenance: Database audit logs require daily review to make certain that there has beenno data misuse. This requires overseeing database privileges and then consistently updating useraccess accounts. A database security manager also provides different types of access control fordifferent users and assesses new programs that are performing with the database. If these tasks areperformed on a daily basis, you can avoid a lot of problems with users that may pose a threat to thesecurity of the database.Varied Security Methods for Applications: More often than not applications developers will varythe methods of security for different applications that are being utilized within the database. Thiscan create difficulty with creating policies for accessing the applications. The database must alsopossess the proper access controls for regulating the varying methods of security otherwise sensitivedata is at risk.Post-Upgrade Evaluation: When a database is upgraded it is necessary for the administrator toperform a post-upgrade evaluation to ensure that security is consistent across all programs. Failureto perform this operation opens up the database to attack.Split the Position: Sometimes organizations fail to split the duties between the IT administrator andthe database security manager. Instead the company tries to cut costs by having the IT administratordo everything. This action can significantly compromise the security of the data due to theresponsibilities involved with both positions. The IT administrator should manage the databasewhile the security manager performs all of the daily security processes.Application Spoofing: Hackers are capable of creating applications that resemble the existingapplications connected to the database. These unauthorized applications are often difficult toidentify and allow hackers access to the database via the application in disguise.Manage User Passwords: Sometimes IT database security managers will forget to remove IDs andaccess privileges of former users which leads to password vulnerabilities in the database. Passwordrules and maintenance needs to be strictly enforced to avoid opening up the database tounauthorized users.Windows OS Flaws: Windows operating systems are not effective when it comes to databasesecurity. Often theft of passwords is prevalent as well as denial of service issues. The databasesecurity manager can take precautions through routine daily maintenance checks.B. DATABASE MANAGEMENT SYSTEM (DBMS) A database management system (DBMS) is a collection of programs that manages thedatabase structure and controls access to the data stored in the database. In a sense, a databaseresembles a very well-organized electronic filing cabinet in which powerful software, known as adatabase management system, helps manage the cabinet’s contents. The figure below shows an overview of the basic concepts of the database and the DBMS
software, known as the Database System. A SIMPLIFIED DATABASE SYSTEM ENVIRONMENT.Database system USERS/PROGRAMMERS APPLICATION PROGRAMS/QUERIES DBMS SOFTWARE SOFTWARE TO PROCESS QUERIES/PROGRAMS SOFTWARE TO ACCESS STRORED DATA
STORED DATABASE STORED DEFINITION (META-DATA) DATABASEE The DBMS serves as the intermediary between the user and the database. The databasestructure itself is stored as a collection of files, and the only way to access the data in those files isthrough the DBMS. The figure below emphasizes the point that the DBMS presents the end user (orapplication program) with a single, integrated view of the data in the database. The DBMS receivesall application requests and translates them into the complex operations required to fulfill thoserequests. The DBMS hides much of the database’s internal complexity from the applicationprograms and users.The application program might be written by a programmer using a programming language such asVisual Basic.NET, Java, or C#, or it might be created through a DBMS utility program. A database management system (DBMS) is a collection of programs that enables users to create and maininvolvesspecifying thedatatypes,structures,andconstraints ofthedata to be stored in the database. The database definition or descriptive information is also stored bythe DBMS in the form of a database catalog or dictionary; it is called meta-data. Constructing the database is the process of storing the data on some storage medium that iscontrolled by the DBMS. Manipulating a database includes functions such as querying the databaseto retrieve specific data, updating the database to reflect changes in the miniworld, and generatingreports from the data. Sharing a database allows multiple users and programs to access the databasesimultaneously. An application program accesses the database by sending queries or requests for data to theDBMS. A query typically causes some data to be retrieved; a transaction may cause some data to beread and some data to be written into the database. Other important functions provided by the DBMS include protecting the database and
maintaining it over a long period of time. Protection includes system protection against hardware orsoftware malfunction (or crashes) and security protection against unauthorized or malicious access.A typical large database may have a life cycle of many years, so the DBMS must be able tomaintain the database system by allowing the system to evolve as requirements change over time.It is not absolutely necessary to use general-purpose DBMS software to implement a computerizeddatabase. We could write our own set of programs to create and maintain the database, in effectcreating our own special-purpose DBMS software. In either case—whether we use a general-purpose DBMS or not—we usually have to deploy a considerable amount of complex software. Infact, most DBMS s are very complex software systems.Having a DBMS between the end user’s applications and the database offers some importantadvantages. First, the DBMS enables the data in the database to be shared among multipleapplications or users. Second, the DBMS integrates the many different users’ views of the data intoa single all-encompassing data repository.Because data are the crucial raw material from which information is derived, you must have a goodmethod to manage such data. The DBMS helps make data management more efficient and effective. In particular, a DBMS provides advantages such as:Improved Data Sharing. The DBMS helps create an environment in which end users have betteraccess to more and better-managed data. Such access makes it possible for end users to respondquickly to changes in their environment.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 datamanipulation—for example, to read or update the data. Simply put, a query is a question, and an adhoc query is a spur-of-the-moment question. The DBMS sends back an answer (called the queryresult set) to the application. For example, end users, when dealing with large amounts of sales data,might want quick answers to questions (ad hoc queries)Such as: What was the dollar volume of sales by product during the past six months? What is the sales bonus figure for each of our salespeople during the past three months? How many of our customers have credit balances of $3,000 or more?Improved Data Security. The more users access the data, the greater the risks of data securitybreaches. Corporations invest considerable amounts of time, effort, and money to ensure thatcorporate data are used properly. A DBMS provides a framework for better enforcement of dataprivacy and security policies.
Minimized Data Inconsistency. Data inconsistency exists when different versions of the same dataappear in different places. For example, data inconsistency exists when a company’s salesdepartment stores a sales representative’s name as ―Andy Colen‖ and the company’s personneldepartment stores that same person’s name as ―Smith A Colen,‖ or when the company’s regionalsales office shows the price of a product as $45.95 and its national sales office shows the sameproduct’s price as $43.95. The probability of data inconsistency is greatly reduced in a properlydesigned database.Improved Decision Making. Better-managed data and improved data access make it possible togenerate better-quality information, on which better decisions are based. The quality of theinformation generated depends on the quality of the underlying data. Data quality is acomprehensive approach to promoting the accuracy, validity, and timeliness of the data. While theDBMS does not guarantee data quality, it provides a framework to facilitate data quality initiatives.Better Data Integration. Wider access to well-managed data promotes an integrated view of theorganization’s operations and a clearer view of the big picture. It becomes much easier to see howactions in one segment of the company affect other segments.Increased End-User Productivity. The availability of data, combined with the tools that transformdata into useful information, empowers end users to make quick, informed decisions that can makethe difference between success and failure in the global economy.METHODS OF DATA ORGANIZATION AND ACCESS Data organization is the permanent logical structure of the file. You tell the computer how toretrieve records from the file by specifying the access mode. Organizing and accessing data are two of the driving forces behind data management.Organizing data involves arranging data in storage so that they may be easily accessed. Accessing data refers to retrieving data from storage. Data organization and access are important determinants of how easily managers and userscan obtain the information they need to do their jobs. Since some organization and access schemesprovide faster or more flexible ways to locate individual records than others, it is important formanagers to anticipate what data they and their subordinates will need when designing files anddatabases.Data Organizing Methods:There are different types of ways to organize data:
Sequential OrganizationA sequential file contains records organized in the order they were entered. The order of the recordsis fixed. The records are stored and sorted in physical, contiguous blocks within each block therecords are in sequence. Records in these files can only be read or written sequentially.Once stored in the file, the record cannot be made shorter, or longer, or deleted. However, the recordcan be updated if the length does not change. (This is done by replacing the records by creating anew file.) New records will always appear at the end of the file.If the order of the records in a file is not important, sequential organization will suffice, nomatter how many records you may have. Sequential output is also useful for report printing orsequential reads which some programs prefer to do.Line-Sequential OrganizationLine-sequential files are like sequential files, except that the records can contain only characters asdata. Line-sequential files are maintained by the native byte stream files of the operating system.Indexed-Sequential OrganizationKey searches are improved by this system too. The single-level indexing structure is the simplestone where a file, whose records are pairs, contains a key pointer. This pointer is the position in thedata file of the record with the given key. A subset of the records, which are evenly spaced along thedata file, is indexed, in order to mark intervals of data records.This is how a key search is performed: the search key is compared with the index keys to find thehighest index key coming in front of the search key, while a linear search is performed from therecord that the index key points to, until the search key is matched or until the record pointed to bythe next index entry is reached. Regardless of double file access (index + data) required by this sortof search, the access time reduction is significant compared with sequential file searches.It is important to note that the hardware for Index-Sequential Organization is usually Disk-based,rather than tape. Records are physically ordered by primary key. And the index gives the physicallocation of each record. Records can be accessed sequentially or directly, via the index. The index isstored in a file and read into memory at the point when the file is opened. Also, indexes must bemaintained.Inverted ListIn file organization, this is a file that is indexed on many of the attributes of the data itself. Theinverted list method has a single index for each key type. The records are not necessarily stored in asequence. They are placed in the data storage area, but indexes are updated for the record keys andlocation.Heres an example, in a company file, an index could be maintained for all productsand another onemight be maintained for product types. Thus, it is faster to search the indexes than every record.These types of file are also known as "inverted indexes." Nevertheless, inverted list files use moremedia space and the storage devices get full quickly with this type of organization. The benefits areapparent immediately because searching is fast. However, updating is much slower.
Direct or Hashed AccessWith direct or hashed access a portion of disk space is reserved and a "hashing" algorithm computesthe record address. So there is additional space required for this kind of file in the store. Records areplaced randomly throughout the file. Records are accessed by addresses that specify their disclocation. Also, this type of file organization requires a disk storage rather than tape. It has anexcellent search retrieval performance, but care must be taken to maintain the indexes. If theindexes become corrupt, what is left might as well go to the bit-bucket, so it is as well to haveregular backups of this kind of file just as it is for all stored valuable data!Data Accessing Methods:There are different ways to access data:Sequential access:Sequential access is a method whereby the records of file are accessed in sequential order. Therecords in a sequential file appear one after another in the order in which they were entered into thecomputer and subsequently stored on the medium. Access to any record requires access to all of thepreceding records. Magnetic tape is a storage medium that is sequential in nature. To access aparticular record on magnetic tape, you must read all of the preceding records first. You could usethe sequential access method to record the individual student grades each week because you mustaccess and update all of the records of the student anyway.Direct access:Direct access also called random access is a method in which the records in a file are stored andaccessed in random order. A direct access file has a key, called a key field or access key, that lets thecomputer locate, retrieve and update any record in the file without reading each preceding record. Akey field is a field that uniquely identifies each record. Account numbers, employee identificationnumber and social security numbers are examples of key fields.
Indexed sequential access:This type of access allows both sequential and direct access of the record in a file. An indexedsequential file can be set up in many ways. Basically records are stored sequentially when theindexed sequential file is created. However, where records are added to the file, they are stored outof sequence in an overflow area.The computer keeps an index of the key fields from each record. It automatically sorts and updatesthe index to allow both sequential and direct access. Then it searches the index by key field toaccess a record. When it finds the key field, it can access the record directly using an addressassociated with the first key field in the sorted index and follows the rest of the index in sequentialorder. The sorted index allow the computer to find records in sequence no matter where they arephysically located on a disk. In practice, multiple indexes usually narrow the location of eachrecord. This type of file access does not work with tape because tape is a sequential access mediumonly. REFERENCESOpel. A, (2011), Databases Demystified, Published by the McGraw-Hill Companies Pages 1 – 3accessed on 03 March, 2013www.management-hub.com About MIS - Role of Database in an Organization.html accessed on04 March, 2013.Coronel, Morris, Rob - Database Systems (Design, Implementation and Management) 9th editionElmasri, Navathe- Fundamentals of DB Systems, 6th Editionhttp://publib.boulder.ibm.com/infocenter/iadthelp/v7r0/index.jsp?topic=/com.ibm.etools.iseries.langref.doc/c0925395156.htm accessed on March 5, 2013http://articles.submityourarticle.com/data-access-and-organization-methods-219812 accessed onMarch 5, 2013
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