Relationship in database
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The document discusses the concept of relationships in database design, detailing various degrees of relationships such as unary, binary, and ternary, along with examples. It explains associative entities and the cardinality of relationships, differentiating between one-to-one, one-to-many, and many-to-many cardinalities. Additionally, the content touches on the optional and mandatory nature of participation in relationships.
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Relationship in database
- 2. Topics: • Relationship • Degree of a relation • Associative entity • Cardinality of relationships •ارتباط •ارتباط درجه •پذیر شرکت موجودیت •ارتباط کاردینالیتی 1:50 AM Gharjistan University Computer Science Faculty Farah Branch 2
- 3. Relationship: • Showing association among two or more than two entity types is called Relationship. •اضا یا و دو بین رابطه دادن نشانفه بنام را موجودیت نوع دو از تر میکند یاد ارتباط. Nangarhar University Computer Sceince Faculty 3
- 4. Continue… Nangarhar University Computer Sceince Faculty 4 Teacher SubjectTeaches
- 5. Degree of a relation: • The number of entity types that participate in a relationship is called its degree. •یک در که موجودیت نوع تعداد درجه بنام میکند شرکت ارتباط میشود یاد ارتباط. Nangarhar University Computer Sceince Faculty 5
- 6. Degree of a relation… • Three most common degree are: 1. Unary Relationship(Degree one). 2. Binary Relationship(Degree two). 3. Ternary Relationship(degree three). •ذیل قرار معمول بسیار درجه سه است: .1یگانه ارتباط(یک درجه) .2دوگانه ارتباط(دو درجه) .3گانه سه ارتباط(سه درجه) Nangarhar University Computer Sceince Faculty 6
- 7. Unary relationship(degree one): • A relation between the instances of single entity type is called Unary(Degree one) Relationship . • An entity type linked with itself, also called recursive relationship. •ن یک های نمونه بین ارتباط یکوع یاد یگانه ارتباط بنام موجودیت میشود. •موجودیت نوع یکخودش با ایکه ارتباط بنام همچنان باشد وصل میشود یاد بازگشتی. Nangarhar University Computer Sceince Faculty 7 person Is_married_to EMPLOYEE Manages
- 8. Binary relationship(degree two): • A relation between the instances of two entity types is called binary(degree two) relationship. •های نمونه بین ارتباط یکنوع دو ارتباط بنام موجودیتیاد دوگانه میشود. Nangarhar University Computer Sceince Faculty 8 Teacher SubjectTeaches
- 9. Ternary relationship(degree three): • A Relationship between the instances of three entity types is called Ternary(Degree three) relationship. • Example: Many venders ships many items to many warehouses. •های نمونه بین ارتباط یکسهنوع ارتباط بنام موجودیتی گانه سهاد میشود. •مثال:اشیای زیاد گان فروشنده انتقال زیاد های گدام به را زیادی میدهد. Nangarhar University Computer Sceince Faculty 9
- 10. Ternary relationship(degree three)… • The Institute might need to record which teachers taught which subjects in which courses. •داشت ضرورت ممکن انستیتیوته استا کدام که کند ثبت تا باشدکدام د درس صنف کدام در را مضمون میدهد. 1:50 AM Gharjistan University Computer Science Faculty Farah Branch 10
- 11. Degree of relationships: Nangarhar University Computer Sceince Faculty 11 Entities of two different types related to each other. Entities of three different types related to each other. One entity related to another of the same entity type.
- 12. Associative entity: • The presence of one or more attributes on a relationship suggests to the designer that the relationship should perhaps be represented as an entity type. • That entity type is called associative Entity. •یک از بیشتر یا و یک موجودیت ب ارتباط یک باالی خاصه صفته ارت که میکند پیشنهاد دیزاینربه باط داده نمایش موجودیت نوع شکل شود. •بنام موجودیت نوع این که میشود یاد پذیر شرکت موجودیت. Nangarhar University Computer Sceince Faculty 12 Nangarhar University Computer Sceince Faculty
- 13. Associative entity example: Nangarhar University Computer Science Faculty 13 STUDENT COURSE Std_id S_name Course_id C_title Certificate Date_comp Certificate_No
- 14. Cardinality of relationships: • One to One: • Each entity in the relationship will have exactly one related entity. • For example: •یک به یک: •یک ًادقیق ارتباط در موجودیت هر داشت خواهد وابسته موجودیت. •مثال بطور: Nangarhar University Computer Sceince Faculty 14 Person Passporthas
- 15. Cardinality of relationships… • One to Many: • An entity on one side of the relationship can have many related entities, but an entity on the other side will have a maximum of one related entity. • For example: •چند به یک: •ارتباط طرف یک در موجودیت یک وابس موجودیت چندین که میتواندته طرف موجودیت اما باشد داشته را وابس موجودیت یک حداکثر دیگرته داشت خواهد. •مثال بطور: Nangarhar University Computer Sceince Faculty 15 Instructor Coursesteaches
- 16. Cardinality of relationships… • Many to Many: • Entities on both sides of the relationship can have many related entities on the other side. •چند به چند: •طرف دو هر در ها موجودیت موجودی چندین که میتواند ارتباطت باش داشته دیگر طرف در وابستهد. 1:50 AM Gharjistan University Computer Science Faculty Farah Branch 16 Student CoursesRegister for
- 17. Mandatory/Optional Relationships: • Participation by an entity in a relationship may be optional or mandatory. • For example: •یک در موجودیت یک شرکت اجباری یا و اختیاری ممکن رابطه باشد. •مثال بطور: Nangarhar University Computer Sceince Faculty 17 Employee CarDrives
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