Element Relationship Modeling and ERDs

Presentation Transcript

Element Relationship Modeling and ERDs

What Will I Learn? In this lesson, you will figure out how to: Define the importance of execution free as it identifies with information models and database outline usage List the four objectives of element relationship displaying Identify a substance relationship graph (ERD)

Why Learn It? An element relationship graph , contracted as ERD , is a steady instrument that can be utilized to speak to information necessities paying little mind to what sort of database is utilized, or regardless of the possibility that a database is utilized by any stretch of the imagination!

execution free A decent calculated information demonstrate remains the same paying little respect to what kind of database the framework is in the long run based on. This is what is mean when we say that the model is "sans execution." The information model ought to remain the same regardless of the possibility that a database is not utilized by any means, for instance if the information is in the long run put away as bits of paper in a file organizer.

The four objectives of ER displaying The four objectives of ER demonstrating: Capture all required data Ensure that data seems just once Model no data that is resultant from other data officially demonstrated Locate data in an anticipated, intelligent place Think of your school record. From your first days in school, information about you was caught. There is likely a record of your unlucky deficiencies, notes on teach, classes taken, and grades earned.

DJs on Demand Read the total business situation for the DJ business underneath. At that point look at the finished ERD. We began as a gathering of companions who sorted out gatherings and redid our own music. At that point we thought we'd transform it into a business to seek after our interests and procure some cash. We called ourselves the "DJs on Demand." Everyone who works here is an accomplice. Each accomplice has a particular duty. The venture chief reaches the customer to talk about the occasion. Is it a birthday gathering, a wedding, a commemoration, a graduation? What is the date for the gathering or occasion?

DJs on Demand Once that is chosen, the occasion organizer connects with the customer about particular areas, providing food, beautifications, and other particular points of interest. The DJ converses with the customer about the sort of music needed. The venture director oversees the occasion organizers and DJs. He/she additionally approves uses identified with a venture. We have an expansive accumulation of CDs. Every CD contains a few tunes, and a similar tune can show up on a few CDs. We jump at the chance to arrange every tune by sort (hip bounce, salsa, R & B (beat and blues), techno, salsa, polka, shake, jazz, new age, traditional, and so on.) We can propose an underlying rundown of tunes to the customer relying upon the occasion. Obviously, a customer can ask for different tunes also.

DJs on Demand Our customer rundown is developing. We have a great deal of rehash business - clients who like what we've done and request that we work their different occasions. We have some exceptionally bustling clients who can have more than one occasion going ahead in the meantime! We likewise have a rundown of topics that we can use to sort these occasions. For instance: a wedding may have a tropical subject, a gathering may have a jamboree topic, a commemoration could have a sixties topic, and so on. This helps us pick a setting and furthermore gives us a thought of what the DJ (and different artists) ought to wear. A few accomplices have a claim to fame or ability - so a subject can likewise help us allocate the opportune individual to the employment.

DJs on Demand Events are held either in an open space or a private home. The occasion director visits both and makes courses of action with people in general space tenant or the private-property holder. Since a few accomplices can deal with an occasion, and an occasion can be doled out to a few accomplices, we get a kick out of the chance to monitor who is chipping away at which occasion. We keep a log of what every occasion organizer and DJ has done on an occasion, and when they did it.

ERD for DJs on Demand

Terminology Key terms utilized as a part of this lesson include: without implementation Entity relationship graph (ERD)

Summary In this lesson, you have figured out how to: Define the significance of execution free as it identifies with information models and database outline usage List the four objectives of substance relationship demonstrating Identify an element relationship chart (ERD)

Some new words tweaked ( 定制 , 用户化 ) accomplice ( 合伙人 , 股东 , 舞伴 , 伴侣 ) commemoration ( 周年纪念 ) cooking ( 公共饮食业 ; 给养 ) extend chief ( 项目管理人 [ 经理 ]) approves ( 批准 ) (Rock "n" roll.【 音乐】 摇滚乐 ) R & B (beat and blues) 节奏和布鲁斯 jazz (20世纪产生于美国的一种舞曲性音乐)爵士乐, 喧闹 hip jump ( 希普霍普 （由快板歌、涂墙艺术、霹雳舞等构成的亚文化） ) salsa ( 拉丁舞 ) polka ( 波尔卡舞 , 女用紧身短上衣 ) new age ( 新世纪 )

Some new words tropical ( 热带的 , 热情的 ) jamboree ( 狂欢节 ) setting ( 会议地点 ) claim to fame ( 专业 ) ability ( 技术专长 ) leaseholder ( 租贷人 ) soundtracks ( 电影的配乐/声道；音带 ) Qualifies ( 限制修饰 ) Classifies ( 分类 , 分等 ) Mandatory ( 命令的 , 强制的 ) twofold check n. 仔细的检查 Oatmeal (( 燕 ) 麦片 , ( 燕 ) 麦粥 ) raisin ( 葡萄干 )