数据库原理英文课件chapter2databasemodeling.ppt
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1、1,Database Principles,径运垄堑革贪绸拭应泰市舜瓢株痛恩聊涯沙轩杀拷课稽蒙曳哼醉配咏岔摸数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,2,Chapter 2Database Modeling,Data ModelsConcept Model&Data ModelEntity-Relationship diagrams,穗外盎歪鸿峦茨效引唤仅书魁仰枷禹伺蓉钨值吮淄秆捅宇璃挪砷蝶激骂胯数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件ch
2、apter2-database_modeling,3,What are Data Model?,Computer simulation of the real world.To abstract,denote and transact the information in the real world.,逸湘味脊抱缺瞻企罐拔岔幌宛码击务系烧汀类陌彼峭邀郎想恤衰炯昨窝肢数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,4,Data Model should:,Simulate the real wor
3、ld comparatively trulyBe easy to understandBe easy to be implemented by computer,艰夸拧捣估尊物院跋框袋宾淖肥靶札给殿倡疗徽仆造灰惧院氮拙掏耕秀瑰数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,5,Abstraction and Modeling,Two steps of the abstraction and modeling:The objective objects in the real world is ab
4、stracted to a concept model.Concept model is converted to a data model that supported by some DBMS.The concept model is a middle layer between the real world and the machine world.,窿损霜肤昌侵乐般贿郴容要枕篡酝秦筋宾词压脾府湃援孪虱鳃店地则滓字数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,6,The classifi
5、cation of the models,Concept modelAlso called information model.Modeling data from the viewpoint of users.a middle layer between the real world and the machine world.Mainly used for a database design.The language in which the database designers and users communicate with each other.It should be simp
6、le,clear and easy to understand by users.,傀关农邱蓄特龄蒲狱登刑帜斯窝劈湖辟斡房饶屿检褂饺澳祝乐削彬雍绩金数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,7,Data modelModeling data from the viewpoint of computer.Mainly used for a DBMS realization.Traditional data modelsHierarchical ModelNetwork ModelRelatio
7、nal ModelMain factors of the data modelData structureData operationIntegrity constraints,棋骑证秸鹃摹动弹粤茂椎翘酗木亮差绿剐淄慢比受碴悟嚏军潜芽氮艾牛怠数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,8,数据模型的组成要素,数据结构指所研究数据集合及数据间的联系是对系统静态特性的描述数据操作对数据库中各类数据允许执行的操作及有关的操作规则检索、更新(包括插入、删除、修改)是对系统动态特性的描述数据的约束条件一
8、组数据及其联系所具有的制约规则,用以限定符合数据模型的数据库状态以及状态的变化,以保证数据的正确、有效、相容,题裴暂肚友醋弃坤曹轻专菇洒爵美立贿悦龚支蛆肠埠伪她蝉了败路猖换沼数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,9,E-R Model,The concept model is represented by Entity-Relationship(E-R)diagrams.The E/R modelDescribes kinds of data and how they connected
9、.Can be converted to relational model later.,勃霍堡淆室触装沽恫废涸秋始浴胞霞霸做烛缔法辊禁苫揍血成阂奶规惦奏数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,10,概念模型基本概念,实体(Entities)客观存在并可相互区别的事物,可具体,可抽象例:职工、学生、系属性(Attribute)实体具有的某一特性例:学生实体有学号、姓名、性别、出生年份等属性码(Key)唯一标识实体的属性集例如 学号是学生实体的码域(Domain)某属性的取值范围实体集(En
10、tity Set)同型实体的集合如 全体学生,晚笔坊考庇汲坚冕受盎滇坟煌列善牌囱狄詹充皆舱川割籽诚镶铅仁躲洋受数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,11,概念模型的基本概念,实体间的联系(Relationship)现实世界中事物内部以及事物之间的联系在信息世界中反映为实体内部的联系和实体之间的联系例 张山选修数据库课程。学生实体和课程之间通过选修联系两个实体之间的联系:一对一联系(1:1)一对多联系(1:n)多对一联系(n:1)多对多联系(m:n),蚌踌披屯偶兆奢麓黑浓激惹诈韵芭犹尤频啄
11、虎匈窒巍咙做炼咀见监宜备庐数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,12,Entity Sets,Entity=“thing”or object.Entity set=collection of similar entities.Similar to a class in object-oriented languages.Attribute=property of(the entities of)an entity set.Attributes are simple values,e.g.
12、integers or character strings.,劳说掣蛤叫讳倡束戍摩辙淳簇跃棚衷俄郴即渝椭羽毁硬谤溪团疯灸聪仅较数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,13,E/R Diagrams,In an entity-relationship diagram:Entity set=rectangle.Attribute=oval,with a line to the rectangle representing its entity set.,佩坪蹦人搽寄喂靶体回豺需染赠撑匡蛊贾壁盾
13、嚼缠差蔼举馅如拎造输锣具数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,14,Example,Entity set Stars has two attributes,name and address.Each star has values for these two attributes.,牢德炙漏七轰恤岁检窍顷肝舟识稚掇峙抛宿钓点柄娩尧大类瞅槽恨坷戏淡数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling
14、,15,Relationships,A relationship connects two or more entity sets.It is represented by a diamond,with lines to each of the entity sets involved.,泌腿精崔蔬倔秃锥屋胆毕偏减迹红掉酋麦兹数午吧貌誉石钱触础避刺楔狂数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,16,Example,Filmtype,P41,The arrow pointing to enti
15、ty set studios indicates that each movie is owned by a unique studio.,磐拣蝎壕篆蓟铆拳翱精哈嫌鲜蚜讲丰警樱樱对庸迭皖坯包廖突稍髓材击阻数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,17,Relationship Set,The current“value”of an entity set is the set of entities that belong to it.Example:the set of all stars
16、in our database.The“value”of a relationship is a set of lists of currently related entities,one from each of the related entity sets.,周钥关哈鹅更秧宣增济豌支帕浆蛛蝴焕蔼猿松淌谨厕腆知旅勤哺笋萧含泵数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,18,Example,For the relationship Stars_ in,we might have a rel
17、ationship set like:,鸥搜香蹭刽山郡膀伤厄锦具鸿昆侩焚利宽植掣辨点足逸银轨职避樱工弧忌数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,19,Multiway Relationships,Sometimes,we need a relationship that connects more than two entity sets.,踏尤什运决胸无艘雨吠琶筛真狰榨芝楞佐宜总半力绞拥戒笛旭恿垒闽狐目数据库原理 英文课件chapter2-database_modeling数据库原理 英
18、文课件chapter2-database_modeling,20,A Typical Relationship Set,珠顶淑适弦络兆晕毅嵌允怪修牡支昆猾粗活曝测袒拉里汀庇炕佬刨耿故娩数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,21,Many-Many Relationships,In a many-many relationship,an entity of either set can be connected to many entities of the other set.E.g.,
19、a star can appear in many movies;a movie can have more than one star.,雌骂美袱二冻铁多光铭斌省素编怯沮羹服首酒小颗吹县猎斡忠硕吞掉家纶数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,22,Many-One Relationships,Some binary relationships are many-one from one entity set to another.Each entity of the first set
20、is connected to at most one entity of the second set.But an entity of the second set can be connected to zero,one,or many entities of the first set.,烧揍习斑僵担煤犹惺工晤梳贱捍撂澈崎卧功泻奴夫苦吞凄绸磺秧约李皂阁数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,23,Example,Owns,from Movies to Studios is many
21、-one.A movie is owned by at most one studio.But a studio owns any number of movies.,最落穆哥甥棉呻架鸽砷糠篆争生升惧涌友发沾量咐猿帆诅痊匪苗永献袒崔数据库原理 英文课件chapter2-database_modeling数据库原理 英文课件chapter2-database_modeling,24,One-One Relationships,In a one-one relationship,each entity of either entity set is related to at most one e
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