(a) Identify four different database types; giving examples

(a) Identify four different database types; giving examples of how their data are structured.Flat Files:A flat file is a simple way to store data. All the records in flat file database have the matching number of fields and specific records have dissimilar data in an individual field with a field that serves as the key to identifying a particular record. An example of this could be that the social security or national insurance number could be the key field in a record of address, name, phone number etc. For an individual or an extension of the land there may be several fields related/linked. When the amount of fields becomes long a flat file is cumbersome to search, the key field is normally determined by the programmer/operator and also the search for other determinants can be very difficult to the users, flat file type of database is simple in its structure development of the number of fields generally includes reprogramming and additionally adding new records takes up a lot of time particularly if there are numerous fields. Flat Files has a 2D structure data and also has a table and is out of the four given databases, the easiest way to set up as well as to utilize. Flat Files work by storing all the given information usually from a business need into a single database which is in one table.  Ref: https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwjW38OJwt_YAhUGL1AKHawACdMQjRwIBw&url=https%3A%2F%2Fwww.colorado.edu%2Fgeography%2Fgcraft%2Fnotes%2Fdatacon%2Fdatacon.html&psig=AOvVaw2Vhz42hvgtq1Lbvi1fMfG4&ust=1516296248131200Relational Database:Relational Database is a type of database which stores the given information or data in multiple tables which are linked to each other through specified relationships. ?A single flat file table is useful for recording a limited amount of data. But a large database of flat files can be inefficient, since it takes up more space and memory than a relational database. It also requires that new data be added every time a new record is inserted, while a relational database does not. Finally, data redundancy, where data is partially duplicated between records, can occur in flat file tables and can be more easily avoided in relational databases.Therefore, if you have a large data set on many different entities, it is more efficient to create separate tables and link them to relationships.Example of Relational database: Image-Ref: https://www.google.co.uk/imgres?imgurl=https%3A%2F%2Fi.ytimg.com%2Fvi%2FiKK3P11OCyM%2Fmaxresdefault.jpg&imgrefurl=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DiKK3P11OCyM&docid=VScbiUQ4M7o4LM&tbnid=Dhn3sn6MDCiKDM%3A&vet=1&w=1280&h=720&bih=734&biw=1536&ved=0ahUKEwjUk5udxN_YAhXPaVAKHR_TAMcQMwj7ASgCMAI&iact=c&ictx=1Network Database: Network Database is a type of database that uses parent/child interfaces to connect data together, one child’s link may be related with any number of parent nodes. Specified record types.Example which could be given is off a Network Diagram which is also a Relationship based diagram as seen below.Another diagram: Image ref: https://www.google.co.uk/url?sa=i=j==s=images==rja=8=0ahUKEwjPtub3-9_YAhWIh7QKHbkCAMgQjRwIBw=http%3A%2F%2Fslideplayer.com%2Fslide%2F1650304%2F=AOvVaw0NjOikCJcRRUBSdVnerfWU=1516311583930173Hierarchal Database:Hierarchal Database is a model which is organized very similar to a tree model with a defined tree structure, the name basically explains how it is set up. ? Image ref:https://www.google.co.uk/url?sa=i=j==s=images==rja=8=0ahUKEwiqn5Sk-9_YAhVMaVAKHbWEDdMQjRwIBw=https%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FFile%3AHire.png=AOvVaw0NjOikCJcRRUBSdVnerfWU=1516311583930173(b) Describe, in simple everyday terminology, the advantages and disadvantages of two, or more of the database types identified in (a) above and an example of when each may be used.Flat Files:Advantages• It is very easy to understand especially to a beginner.• Records are usually sorted out nicely in one table which makes it very easy to filter and search through.Disadvantages  • It is hard to update the database because there’s huge amounts of data.• Flat Files have very low security which makes it easy for hackers to gain access. Relational Database:Advantages• This database reduces Data Redundancy as data is only stored once.• This database has better security thus people can’t access confidential information.Disadvantages  • This database can be expensive to set up as well as to maintain. Problem’s that can occur in maintain database is that it can slow doing  • The database can become very complex when it has lots of records thus can create problems.Task 2Prepare a presentation or report to describe, with worked examples, the analysis and design methodologies – logical data modelling (LDM) and normalisation. Logical Data ModellingIn this report I will also go over the 3 main components related with LDM which being an Entity, a Relationship and an AttributeAn Entity is any real thing that we wish to recognise as a separate object, person or event within the database. An example of this would-be: Customer Table, Video Table and Appointment Table.An Entity is made of many Attributes such as a Customer entity would have attributes Customer I.D First Name, Surname, Date of Birth, Address etc.A Relationship is association that exists between these entities and is one-to-one, a good example would be of video games and customers which have a direct relationship.These relationships can be shown in an Entity Relationship Diagram such as in the diagram below:The diagram above is made up of 2 components being the entity to represent the database tables and relationships, which represent the link between tables. Thus, things that are entity in the diagram are things like Staff Number, Nurses Surname etc. Data Dictionary is an essential information of the data in a database. It represents table and fields that it will use to build a relational database.The diagram above illustrates a Network Diagram and is a Relationship diagram as it lines are connected to similar colour thus stringing the process forward.Another example of a relationship based diagram on the next pageNormalisationNormalisation are a set of rules devised by Dr Codd, which are used in a Data Modelling Process. It basically is that normalisation is a set of guidelines to help people design the most efficient database structure possible.In this report I will inform about the Advantages of Normalisation as well as its 3 Forms.Advantages:• Prevents Data Redundancy – It basically removes having to repeat and store the same information again and again which could lead to unwanted increase in size. • Prevents Data Anomalies – This is basically preventing inconsistent data, which might be stored about the same person and just useless silly errors. First Normal Form (1NF)These are attributes split into separate data groups having broken out from repeated groups.Second Normal Form (2NF)Focuses on those entities which have a composite key such as a primary key that encompasses more than one attribute.Third Normal Form (3NF)To achieve Third Normal Form no attribute must be dependent on a non-key attribute. ?Explain the purpose of each step in your example of the production of a LDM (often referred to as an ERD or Entity Relationship Diagram and in the execution of normalisation to third normal form.Task 3Discuss the benefits of logical data modelling from the viewpoint of a database developer.Logical Data ModellingLogical Data Modelling is a specific tailored type of a database management system. Logical Data Modelling represents the specific entities, attributes and relationships, which are involved in a business function. The whole model is the basis for the further creation of Physical Data Modelling. A Logical Data Modelling contains various aspects such as entities, attributes, relationships, unique identifiers that are primary keys, subtypes and super types, domain model objects.A logical data model is a graphical representation of the information requirements of acommercial area, it is not a database.Word logic is very critical because it changes the modelling of phrase data to a larger onespecific activity. A logical data model is independent of a physical data storage device.This is the key concept of the logical data model. The reason why a logical data modelit must be independent of technology is simply because technology is changing so rapidlyImage ref: https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwi03M2F9N_YAhUREVAKHdh9CdEQjRwIBw&url=http%3A%2F%2Fsearchdatamanagement.techtarget.com%2Ffeature%2FData-modeling-for-the-business-What-is-a-data-model&psig=AOvVaw3KJCvnVT9booBOuhz-6LOv&ust=1516309718081765Benefits of Logical Data Modelling There are distinct reasons for building a Logical Data Model from the developer’s point of view such as:• It helps mutual understanding of business data requirements and elements.• Provides a nice foundation for designing a database.• It also decreases the maintenance time and cost of its development.• It allows data to be used again as well as be shared.• It avoids data redundancy and ultimately prevents inconsistency in data and business transactions.Benefits for a logical data modelEasy to understandLogical data models are easy to understand for most users; This basically means that most people can identify what information is entered in the database; This is because all attributes, entities and relationships are clearly listed, so it is easier to understand.Easy viewing of business activityLogical data models also help the user to identify the business activities. This is an advantage because it easily identifies the type of information related to the activity, for example:Customer IDAddressName, etc.Construction of LDM and ERDWhen constructing the logical model of data itself, it is very simple because all information is presented clearly; The other use for construction is that it does not take long for small databases, all information is transferred to a diagram with fewer words.Once all the business requirements for a proposed database have been met, it is necessary to model them. Templates are created to visually represent the proposed database so that business needs can be easily associated with objects in the database to ensure that all requirements have been collected complete and accurate. Generally, diverse types of diagrams are produced to illustrate the processes, rules, entities and organizational units that have been identified. These diagrams often include entity relations diagrams, process flowcharts, and server model diagrams. An entity relations diagram (ERD) represents the entities or groups of information and their relationships maintained for a company. Process flowcharts represent business processes and the flow of data between different processes and entities that have been defined. The server model diagrams represent a detailed image of the database that is transformed from the business model into a relational database with tables, columns, and constraints. In essence, data modelling serves as a link between business needs and system requirements.Logical modelling deals with gathering business requirements and converting these requirements into a model. The logical model revolves around the needs of the business, not the database, although the needs of the company are used to establish the needs of the database. Logical modelling involves gathering information about business processes, business entities (data categories) and organizational units. After gathering this information, diagrams and reports are produced that include diagrams of relationships between entities, business process diagrams, and, finally, process flow diagrams. The diagrams produced should show the existing processes and data, as well as the relationships between business processes and data. Logical modelling must accurately represent a visual representation of the activities and data relevant to a particular business.

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