The Evolution Of Database Management System

The Evolution Of Database Management System In the ancient times when there was no computer, the data began to be stored in voluminous data repositories, called books. And eventually with the improvement in technology and expansion in knowledge the whole communities of books transferred to the first real database libraries. The main objective of the database is to ensure that data can be stored and retrieved easily and effectively. It is a compilation of data (records) in a structured way. In a database, the information is stored in a tabular form where data may or may not be interlinked. Hence we can say that basically database is a compilation of database files and each database file is further a collection of records. Database models: Flat files (1960s 1980s): Flat file database is a database that stores information in a single file or table. In a text file, every line contains one record where fields either have fixed length or they are separated by commas, whitespaces, tabs or any other character. In a flat file database, there is no structural relationship among the records and they cannot contain multiple tables as well. Advantages: Flat file database is best for small databases. It is easy to understand and implement. Fewer skills are required to handle a flat file database. Less hardware and software skills are required to maintain a flat file database. Disadvantages: A flat file may contain fields which duplicate the data as there is no automation in flat files. If one record is to be deleted from the flat file database, then all the relevant information in different fields has to be deleted manually making the data manipulation inefficient. Flat file database waste the computer space by requiring it to keep the information on items that are logically cannot be available. Information retrieving is very time consuming in a large database. Implementation of a flat file database: Flat file database is implemented in: Berkeley DB SQLite Mimesis TheIntegrationEngineer etc. Hierarchical database (1970s 1990s): As the name indicates, hierarchical database contains data in a hierarchically-arranged data. More perceptively it can be visualized as a family tree where there is a parent and a child relationship. Each parent can have many children but one child can only have one parent i.e.; one-to-many relationship. Its hierarchical structure contains levels or segments which are equivalent to the file systems record type. All attributes of a specific record are listed under the entity type. In hierarchical database, the entity type is the main table, rows of a table represent the records and columns represent the attributes. In the above figure, CUSTOMER is the parent and it has two children (CHCKACCT SAVEACCT). Advantages: In a hierarchical database pace of accessing the information is speedy due to the predefined paths. This increases the performance of a database. The relationships among different entities are easy to understand. Disadvantages: Hierarchical database model lacks flexibility. If a new relationship is to be established between two entities then a new and possibly a redundant database structure has to be build. Maintenance and of data is inefficient in a hierarchical model. Any change in the relationships may require manual reorganization of the data. This model is also inefficient for non-hierarchical accesses. Network database (1970s 1990s): The inventor of network model is Charles Bachmann. Unlike hierarchical database model, network database allows multiple parent and child relationships i.e., it maintains many-to-many relationship. Network database is basically a graph structure. The network database model was created to achieve three main objectives: To represent complex data relationships more effectively. To improve the performance of the database. To implement a database standard. In a network database a relationship is referred to as a set. Each set comprises of two types of records, an owner record which is same as parent type in hierarchical and a member record which is similar to the child type record in hierarchical database model. Advantages: The network database model makes the data access quite easy and proficient as an application can access the owner record and all the member records within a set. This model is conceptually easy to design. This model ensures data integrity because no member can exist without an owner. So the user must make an owner entry and then the member records. The network model also ensures the data independence because the application works independently of the data. Disadvantages: The model lacks structural independence which means that to bring any change in the database structure; the application program must also be modified before accessing the data. A user friendly database management system cannot be established via network model. Implementation of network database: Network database is implemented in: Digital Equipment Corporation DBMS-10 Digital Equipment Corporation DBMS-20 RDM Embedded Turbo IMAGE Univac DMS-1100 etc. Relational database (1980s present): Relational database model was proposed by E.F. Codd. After the hierarchical and network model, the birth of this model was huge step ahead. It allows the entities to be related through a common attribute. So in order to relate two tables (entities), they simply need to have a common attribute. In the tables there are primary keys and alternative keys. Primary keys form a relation with the alternative keys. This property makes this model extremely flexible. Thus using relational database ample information can be stored using small tables. The accessing of data is also very efficient. The user only has to enter a query, and the application provides the user with the asked information. Relational databases are established using a computer language, Structured Query Language (SQL). This language forms the basis of all the database applications available today, from Access to Oracle. Advantages: Relational database supports mathematical set of operations like union, intersection, difference and Cartesian product. It also supports select, project, relational join and division operations. Relational database uses normalization structure which helps to achieve data independence more easily. Security control can also be implemented more effectively by imposing an authorization control on the sensitive attributes present in a table. Relational database uses a language which is easy and human readable. Disadvantages: The response to a query becomes time-consuming and inefficient if the number of tables between which the relationships are established increases. Implementation of Relational Database: Oracle Microsoft IBM My SQL PostgreSQL SQLite Object-oriented database (1990s present): Object oriented database management system is that database system in which the data or information is presented in the form of objects, much like in object-oriented programming language. Furthermore, object oriented DBMS also facilitate the user by offering transaction support, language for various queries, and indexing options. Also, these database systems have the ability to handle data efficiently over multiple servers. Unlike relational database, object-oriented database works in the framework of real programming languages like JAVA or C++. Advantages: If there are complex (many-to-many) relationships between the entities, the object-oriented database handles them much faster than any of the above discussed database models. Navigation through the data is much easier. Objects do not require assembly or disassembly hence saving the coding and execution time. Disadvantages: Lower efficiency level when data or relationships are simple. Data can be accessible via specific language using a particular API which is not the case in relational databases. Object-relational database (1990s present): Defined in simple terms, an object relational database management system displays a modified object-oriented user-display over the already implemented relational database management system. When various software interact with this modified-database management system, they will customarily operate in a manner such that the data is assumed to be saved as objects. The basic working of this database management system is that it translates the useful data into organized tables, distributed in rows and columns, and from then onwards, it manages data the same way as done in a relational database system. Similarly, when the data is to be accessed by the user, it is again translated from processed to complex form. Advantages: Data remains encapsulated in object-relational database. Concept of inheritance and polymorphism can also be implemented in this database. Disadvantages: Object relational database is complex. Proponents of relational approach believe simplicity and purity of relational model are lost. It is costly as well. Web enabled database (1990s present): Web enabled database simply put a database with a web-based interface. This implies that there can be a separation of concerns; namely, the web designer does not need to know the details about the DBs underlying design. Similarly, the DB designer needs to concern himself with the DBs web interface. A web enabled database uses three layers to function: a presentation layer, a middle layer and the database layer. Advantages: A web-enabled database allows users to get the information they need from a central repository on demand. The database is easy and simple to use. The data accessibility is easy via web-enabled database. Disadvantages: Main disadvantage is that it can be hacked easily. Web enabled databases support the full range of DB operations, but in order to make them easy to use, they must be dumped down.

Free Macbeth Essays: The Importance of Sleep -- Free Essay Writer

The Importance of Sleep in Macbeth  Ã‚      The image of sleep is consistently mentioned in Macbeth with the intention of creating a symbolic importance.   Macbeth himself notes that the sleep he discusses with us, is that that ‘knits up’, meaning the sleep which smoothes out and pieces together. Macbeth recites this after he has spoken to Lady Macbeth directly after he committed the bloody murder of King Duncan.   He cried, ‘Sleep no more!’ to all the house:’Glamis hath murder’d sleep, and therefore Cawdor Shall sleep no more, Macbeth shall sleep no more!’ He frantically and almost deliriously raves, which highlights his conscience, is already bothering him.    The image of sleep is symbolized by Shakespeare to highlight one of the plays themes, conscious.   In reality sleep rests the mind, refreshes the mind and eases a person allowing them to function normally.   It is a fact that a person cannot survive without sleep†¦Ã‚   And Macbeth as well as Lady Macbeth’s characters demonstrate this.   They both will never be at peace again†¦&nb...

Junk Food Essay Essay

For the last thirty years, junk food has been part of our daily life. Whenever we are hungry, we want to celebrate, or have a quick easy meal, we resort to fast food. In this way, pizza, hamburgers, carbonated beverages (sodas), fried chicken, among others, have replaced the nutritious foods in our diet. But this is not the healthy way to nourish ourselves. In my opinion, junk food is certainly not the healthier option when we have to choose what to include in our diet. I clearly know and agree with doctors that junk food consumption must be controlled. Yet, do people really know the consequences this fatty, lack of protein food, have in our body at the time of eating them? To begin with, obesity has a strong bond with fast food. Eating junk food regularly and having a sedentary lifestyle leads to obesity. Obesity leads to other complications like increase in the cholesterol level, blocking of the arteries, the increased risk of coronary diseases, in addition to the physical discomfo rt that extra weight causes. As fast food is addictive it is very difficult to give up on these fatty foods and carbonated drinks and switch to healthier options. That is why I conceder that junk food must not have an essential role in our diet. Furthermore, junk food has too much fat, and too much saturated fat in the diet will cause people to put on weight and get fat or obese. For the opposite, healthy foods contain more vitamins and minerals, lower levels of sodium and chemical additives, and healthier oils and fats. Junk food is high in calories but low in useful vitamins or minerals and it often gets many of its calories from unhealthy saturated fats. That is why, if all the calories that are consumed are from saturated fats, we will be replacing the healthy food for the unhealthy saturated one. Junk food also contains extra salt than the nutritious food and it is unhealthy for the heart, and can cause coronary heart disease. Sugar is essential in junk food as it makes it tast e so good. Soft drinks, cordials, biscuits, cakes and lollies all have a lot of sugar. However, too much sugar makes people fat, rots the teeth, is bad for the blood and may cause other diseases. We can observe that the harm fast food means to our body is a fact to consider controlling the amount of junk food we eat, and avoid a regular intake. In addition, the advertisement fast food restaurants have, such as Mc Donald’s, Burger King, Pizza Hut or Taco Bell is really efficient and has an important role on the increase of obesity all over the world. In the United Kingdom, the Children’s Food Bill is intended to highly regulate the advertising of such food aimed at children, and many other countries are looking forward to do the same. Advertisement helps to increase the consumption of junk food, so, in my opinion, it must be also controlled by the government in order to lower the great number of obese people, harmed by the junk food. Despite the fact that junk food does not have all the nutrients we need to nourish our body, it can definitely be included in our menu, exercising a proper control over their consumption. That is to say, that the benefits of fast food, such as the taste, easy access, instant delivery and affordability can be enjoyed in a correct way if we follow a balanced diet, and in that way it would not cause harm to the body. Taking every argument into consideration, it is clear that fast food risks definitely outnumber its positive effects. The drawback of fast foo d is that it has almost zero nutritious value. The desire of fast food among children and adults is so much that it has been installed in our daily life, and one cannot avoid its consumption. To conclude, it is not wrong to eat junk food sometimes, provided that it is included in a balanced nutritious diet, controlling the correct amount of it.

Risk Management System ( Name Rms ) - 1678 Words

10. Risk Management 10.1 Name Risk Management System (Name RMS) Name Risk Management System (Name RMS) aims to effectively and efficiently manage and assess all the critical risks due to both external and internal factors with the suitable action plans on specific risks, which gives the least possible adverse effects to the customers and company. The holistic framework of the system includes 4 key steps: risk planning, risk assessment, risk handling and risk monitoring showed in Figure 1. Figure 1: Name RMS process layout1 10.2 Risk Planning The project manager such as the product creator in Name Company takes the responsibility of reviewing the risk assessment documents and tracking the progress of control measures with†¦show more content†¦The PESTEL analysis model is firstly applied to identify the external risks from the light switch products which impact the surrounding business environment. The PESTEL model includes 5 different aspects of external risk factors such as Political, Economic, Social, Technological, Environmental and Legal. To complete the risk identification, the internal risks is required to consider by understanding 4 key areas to the company like Strength, Weakness, Threats and Opportunities in the SWOT analysis model. By thinking the company’s internal factors such as Strength and Weakness and finding out the potential external factors such as Opportunities and threats from the environment to the company, help to establish better mitigation measures and strategies to prevent uncertainties events and serious consequences to occur in short term and future. Both of the model results can be found in Appendix. The risk register spreadsheet tool called Circa RiskCom spreadsheet tool is employed for a good and detailed risk assessment table which is shown in Appendix. It combines the both analysis models with residual risk assessment and evaluation of control strategy costs. The risks are split into 3 categories like L– Least, M–Medium and H–Highest for assessing the likelihood and severity consequences of each key risk. 10.3.2 Risk Analysis From the risk