ITEC 3220 Lecture Notes - Lecture 1: Candidate Key, Visual Basic, Business Rule

12 views3 pages

mraliice

13 Dec 2021

School

York University

Department

Information Technology

Course

ITEC 3220

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Select c_name, c_address from candidate_skills where (skill_1 = vb6" and exp_1 > 3 ) or ( skill_2 = The line above might look bad meaning not optimized we should consider alternatives. Basically, we want to optimize meaning alternative design, schema integration, not every integrity constraint can be expressed in erd. Erm does not provide: criteria for schema evaluation, algorithms for schema refinement. Decomposition: basically the relation schema which means table, is replacement by 2 or more r schema such that we get all attributes from original schema. Example: r = (a, b, c, d, e, f) turns into. R1 = (a, b, d) , r2 = (b, c, e, f) R1 = (a, b, d) , r2 = (c, e, f) Definition: a subset depends on its parent, a -> b. If for any possible pair of tuples t1 and t2 from any instance opf r the following holds: If t1. a = t2. a, then t1. b = t2. b.

Related Questions

For many of us, smartphones have become indispensable, but they have also come under fire
for their impact on the way we think and behave, especially among children. Two of the largest
investors in Apple Inc. are urging the iPhone maker to take action against smartphone addiction
among children over growing concerns about the negative effects of technology. An open letter
to Apple on January 6, 2018 from New York-based JANA Partners and the California State
Teachers’ Retirement System (CalSTRS) stated that the firm must do more to help children
fight smartphone addiction. These two shareholders together control about $2 billion in Apple
stock. The investors’ letter urged Apple to offer tools to prevent smartphone addiction and to
provide more parental options for monitoring children’s smartphone usage. The iOS operating
system for Apple smartphones and tablets already has limited parental controls for restricting
Examiners: Dr. Emmanuel Awuni and Dr. Acheampong Owusu Page 2 of 4
apps, features such as location sharing, and access to certain types of content. The investors
felt Apple needs to do more—for example, enable parents to specify the age of the user of the
phone during setup, establish limits on screen time, select hours of the day the phone can be
used, and block social media services.
The average American teenager who uses a smartphone receives his or her first phone at age
10 and spends over 4.5 hours a day on it (excluding texting and talking). Seventy-eight percent
of teens check their phones at least hourly and 50 percent report feeling “addicted” to their
phones. The investors’ letter cited a number of studies on the negative effects of heavy
smartphone and social media use on the mental and physical health of children whose brains
are still developing. These range from distractions in the classroom to a higher risk of suicide
and depression. A recent survey of over 2,300 teachers by them Center on Media and Child
Health and the University of Alberta found that 67 percent of the teachers reported that the
number of students who are negatively distracted by digital technologies in the classroom is
growing. Seventy-five percent of these teachers think students’ ability to focus on educational
tasks has decreased. Research by psychology professor Jean Twenge of San Diego State
University found that U.S. teenagers who spend 3 hours a day or more on electronic devices
are 35 percent more likely, and those who spend 5 hours, or more are 71 percent more likely,
to have a risk factor for suicide than those who spend less than 1 hour. This research also
showed that eighth-graders who are heavy users of social media have a 27 percent higher risk
of depression. Those who spend more than the average time playing sports, hanging out with
friends in person, or doing homework have a significantly lower risk. Additionally, teens who
spend 5 or more hours a day on electronic devices are 51 percent more likely to get less than 7
hours of sleep per night (versus the recommended 9).
Nicholas Carr, who has studied the impact of technology on business and culture, shares these
concerns. He has been highly critical of the Internet’s effect on cognition, and these cognitive
effects extend to smartphone use. Carr worries that excessive use of mobile devices diminishes
the capacity for concentration and contemplation. Carr recognizes that smartphones provide
many useful functions in a very handy form. However, this extraordinary usefulness gives them
too much influence on our attention, thinking, and behaviour. Smartphones shape our thoughts
in deep and complicated ways, and their effects persist even when we aren’t using the devices.
Research suggests that the intellect weakens as the brain grows dependent on the technology.
Carr points to the work of Adrian Ward, a cognitive psychologist and marketing professor at
the University of Texas at Austin, who for a decade has been studying how smartphones and
the Internet affect people’s thoughts and judgment. Ward has observed that using a smartphone,
or even hearing one ring or vibrate, produces distractions that make it harder to concentrate on
a difficult problem or job. Divided attention impedes reasoning and performance.
A study published in Applied Cognitive Psychology in April 2017 examined how smartphones
affected learning in a lecture class with 160 students at the University of Arkansas at
Monticello. It found that students who didn’t bring their phones to the classroom scored a full
letter-grade higher on a test of the material presented than those who brought their phones. It
didn’t matter whether students who brought their phones used them or not. A study of 91 U.K.
secondary schools, published in 2016 in the journal Labour Economics, found that when
schools ban smartphones, students’ examination scores go up substantially, and the weakest
students benefit the most. Carr also observes that using smartphones extensively can be
detrimental to social skills and relationships. Connecting with “friends” electronically via
smartphones is not a substitute for genuine person-to-person relationships and face-to-face
conversations.

rubyarmadillo521

ITEC 3220 Lecture Notes - Lecture 1: Candidate Key, Visual Basic, Business Rule

Document Summary

Get access

Related Documents

CSC343H1 Study Guide - Final Guide: Superkey, Data Integrity, Foreign Key

ECE356 Study Guide - Final Guide: Opossum, Local Variable, Functional Dependency

COMPSCI 186 Study Guide - Midterm Guide: Sorting Algorithm, Good Luck!!, Foreign Key

Related Questions