2.4 - Describe the three-schema architecture. Why do we need mappings between schema levels? How do different schema definition languages support this architecture?
Answer:
DBMS defines three – schema architecture which is shown below:
Internal schema at the internal level to describe physical storage structures and access paths, typically uses a physical data model.
Conceptual schema at the conceptual level describes the structure and constraints for the whole database for a community of users. These uses a conceptual or an implementation data model.
External schemas at the external level to describe the various user views. Usually uses the same data model as the conceptual schema.
The goal of the three-schema architecture is to separate
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the user applications from the physical database. In this architecture, schemas can be defined at the following three levels: The internal level has an internal schema. The conceptual level has a conceptual schema. The external or view level includes a number of external schemas os user views The tree schemas are only descriptions of data that are stored data that actually exists is at the physical level only. The DBMS must transform a request specified on an external schema into a request against the conceptual schema, and then into a request on the internal schema for procession over the stored database. If the request is a database retrieval, the data extracted from the stored database must be reformatted to match the user’s external view. The processes of transforming requests and results between levels is mapping. 2.7 - Discuss the different types of user-friendly interfaces and the types of users who typically use each. Answer: The user-friendly interfaces means which are simple to install, easy to update, pleasant, efficient, easy to remove, and effective error handling. There are ten types of user-friendly interfaces: Touch-user interfaces: are graphical user interfaces using a touchpad or touchscreen display as a combined input and output device Web-based interfaces: hat accept input and provide output by generating web pages which are transmitted via the Internet and viewed by the user using a web browser program. Command-line interfaces: where the user provides the input by typing a command string with the computer keyboard and the system provides output by printing text on the computer monitor. Voice-user interfaces: makes human interaction with computers possible through a voice/speech platform in order to initiate an automated service or process. Menu-based interfaces for web clients or browsing: These interfaces present the user with lists of options that lead the user through the formulation of a request. Forms-based interfaces: These interface displays a form to each user. These interface is designed for naive users. Graphical user interfaces: A GUI typically displays a schema to the user in diagrammatic form. The user then can specify a query by manipulating the diagram. Natural language interfaces: These interfaces accept requests written in English or some other language and attempt to understand them. Interfaces for parametric users: A small set of operations that must be performed repeatedly by parametric users like bank tellers. Interfaces for the DBA: Most database system contain privileged commands that can be used only by the DBA's staff. 2.14 If you were designing a Web-based system to make airline reservations and sell airline tickets, which DBMS architecture would you choose from Section 2.5? Why? Why would the other architectures not be a good choice? Answer: I‘ll choose Three-Tier Client/Server Architecture for Web Application. As the Client will consist of Web User Interface. The Web Server will contain the application for logic which includes all the rules and regulations related to the reservation process and it also include the issue of tickets which is the Database Server containing the DBMS. For a web-based system, a centralized DBMS Architecture will not work since the user interface and database server are on different machines. Basic Client/Server Architecture and Two-Tier Client/Server Architecture would work if the Business Logic can reside on server other than the DBMS Server. In general, if the business logic was on the DBMS Server, it will put an excessive burden on the server. If the business logic were to reside on the web client, it will burden the communication network as well a possibly thin client. Q) Explain the difference between physical and logical data independence. Answer: Physical data independence can modify the physical scheme without making it necessary to rewrite application programs. Such modifications include changing from unblocked to blocked record storage, or from sequential to random access files. Logical data independence can modify the conceptual scheme without making it necessary to rewrite application programs. Such a modification might be adding a field to a record; an application program’s view hides this change from the program. Q) List four significant differences between a file-processing system and a DBMS. Answer: A database coordinates the physical and logical access to the data; a file-processing system only coordinates physical access to the data A DBMS reduces the amount of data duplication A DBMS is designed to allow flexibility in what queries give access to the data, where a file-processing system only allows pre-determined access to data (by specific compiled programs) A DBMS is designed to coordinate and permit multiple users to access data at the same time. A file processing system is much more restrictive in simultaneous data access Q) List five responsibilities of a database management system. For each responsibility, explain the problems that would arise if the responsibility were not discharged. Answer: The five responsibilities of a database management system are: a.
interaction with the file manager.
No DBMS can do without this. If there is no file manager interaction then nothing stored in the files can be retrieved.
b. integrity enforcement.
Consistency constraints may not be satisfied, for example an instructor may belong to a non- existent department, two students may have the same ID, account balances could go below the minimum allowed, and so on.
c. security enforcement.
Unauthorized users may access the database, or users authorized to access part of the database may be able to access parts of the database for which they lack authority. For example, a low-level user could get access to national defense secret codes, or employees could find out what their supervisors earn (which is presumably a secret).
d. backup and recovery.
Data could be lost permanently, rather than at least being available in a consistent state that existed prior to a failure.
e. concurrency control.
Consistency constraints may be violated despite proper integrity enforcement in each transaction. For example, incorrect bank balances might be reflected due to simultaneous withdrawals and deposits on the same account, and so
on. Q) What are five main functions of a database administrator? Answer: Five main functions of a database administrator are: ·To create the scheme definition ·To define the storage structure and access methods ·To modify the scheme and/or physical organization when necessary ·To grant authorization for data access ·To specify integrity constraints
Research My first research experience took place from the Fall 2012 – Summer 2013 in a neurobiology laboratory (Dr. Daniel Plas) focused on Parkinson’s Disease. In this project an undergrad student and I were tasked with optimizing a cellular medium for neural growth of the model organism Lymnaea stagnalis. This was comprised of following established protocols and altering certain variables within the formulas (differing concentrations of ions, pH, et al.) to observe growth pattern differences in vitro.
conceptualization of the term/concept, and it also helps to show that the concept is indeed
1. (45 pts) For each major (CS, IT, DET, IS), identify three important and uniquely identifying characteristics and describe how the four types of professionals would work together in a professional setting. Include information learned from the various instructors for each discipline. How do professionals from these areas work together?
A model is a simplified representation of the structure and content of a phenomenon or system that describes or explains the complex relationships between concepts within the system and integrates elements of theory and practice (Creek et al 1993).
A child’s schema can be seen as part of their inspiration for learning, their unquenchable drive to move, illustrate, discuss, and inquire about (Phillips & Pearce, 2011). According to Woolfolk, Winne and Perry, “schemas (sometimes called schemata) are abstract knowledge structures that organize vast amounts of information” (2015, p. 277). These schemas are mental structures that escort an individuals perception and comprehension of known and unknown experiences and allow an individual to symbolize large amounts of complex data, make assumptions, and make sense of new information (2015). Through the gathering of additional research, it was noted that the term schema possess several definitions as defined by various individuals. These various
A database is a structured collection of data. Data refers to the characteristics of people, things, and events. Oracle stores each data item in its own field. For example, a person's first name, date of birth, and their postal code are each stored in separate fields. The name of a field usually reflects...
Later in the chapter it shows examples of the models created for the business, application and technology layer. Gives us specific techniques and terms needed that are used in the models.
Concept hierarchies organize data or concepts in hierarchical forms or in certain partial order, these are used for expressing knowledge in concise, high-Ieve1 terms, and facilitating mining knowledge at multiple levels of abstraction. Concept hierarchies are also utilized to form dimensions in multidimensional databases and thus are essential components for data warehousing as well. In areas other than data mining, concept hierarchy is commonly called taxonomy. We adopt the term concept hierarchy because of its popularity in the community of data mining and knowledge discovery.
Problems may also occur with the locking mechanism within concurrency control, two examples of such problems are:
The author defines schemata as how our mind relates our past experiences and reactions to the new things we perceive through our sight. Sometimes when the things we see fit our expectation and our schemata, our past experiences help us to interpret. But when we see things that are different from our experiences and unexpected, our schemata can sometimes confuses our minds and causes misinterpretation - seeing things the way we want them to be. The function of schemata can be illustrated by the following example. Some people cannot swim or even hydrophobia because they have been pushed into the water or drowned when they were small, not because they didn't learn. For these people, the first interpretation they have when they see a swimming pool would probably be "it is a very dangerous place where you might be drowned, so don't go near it!" For some of them, no matter how hard you try to make them understand that swimming doesn't equal drowning, they will never try to go into the swimming pool. But for some of them who might be persuaded to try to overcome this challenge would find out that swimming pool is actually not dangerous if you know how to swim; after that, they will have a completely different interpretation of swimming pool. In this example, people who remain terrified of the swimming pool are making a misinterpretation by selecting the wrong schemata which relates to their past experiences. People who later learned not to be afraid of swimming have selected new schemata to interpret swimming pool.
Schemas are not necessarily good or bad Schema concept “ Another concept
There are different forefathers of RDF. The first who defined RDF was MCF a project started by Ramanthan V.Guha at apple computer between 1995 and 1997.he left the apple computer and joins Netscape and start working with Tim Brey on MCF to employ XML to produce first version of RDF. In 1999, RDF was defined by W3C to create RDF Data model by using XML.In2004, work on RDF is continued and produces a group of related specification. The W3C continued to work on RDF data model defined in 1999 and continue to develop new and improved specifications.W3C arrange a workshop in 2010 to discuss with their members the changes and improvements in RDF.
Mainly, there are different types sub-categorized from schemata, namely, linguistic, formal schemata, content schemata and cultural schemata which affect the comprehension and appreciation of the text.
...and stored and recorded for the person that is storing in it for whatever reason. Which is an improvement because I knew that databases were important but I didn’t properly understand how much work went in to performing one action in a system from entry to the final stage of the information be stored in a violent medium and then transfer to a more stable server And how databases are usually thought of as not important part of how a system works. But they are and it is
Better data recovery because a log is kept of disk activities so if there is a disk failure; Windows can restore the disk based on the log file.