IB Computer Science Topic A.2.7 Relationships in Databases Revision Notes (SL/HL)

IB Computer Science Topic A.2.7 Relationships in Databases Revision Notes (SL/HL) | RevisionDojo

Mapped Relationships

One-to-One (1:1): Each record in Table A is linked to only one record in Table B, and vice versa.
One-to-Many (1:M): A record in Table A can be linked to multiple records in Table B, but each record in Table B is linked to only one record in Table A.
Many-to-Many (M:N): Records in Table A can be linked to multiple records in Table B, and vice versa.

Example

One-to-one relationship:
- A person has one passport, a passport belongs to one person.
- Tables: Person and Passport

PersonID	Name	PassportID
1	Alice	101
2	Bob	102

PassportID	IssueDate
101	2020-01-01
102	2021-02-15

One-to-Many relationship:
- A teacher can have many students, but each student has only one teacher.
- Tables: Teacher and Student

TeacherID	Name
1	Mr. Smith
2	Ms. Johnson

StudentID	Name	TeacherID
101	Alice	1
102	Bob	1
103	Charlie	2

Many-to-many relationship:
- Students enroll in multiple courses, and courses have multiple students.
- Tables: Student, Course, and Enrollment (junction table)

StudentID	Name
101	Alice
102	Bob

CourseID	Title
201	Math
202	Science

StudentID	CourseID
101	201
101	202
102	201

How Relationships are Represented

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Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

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Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Mapped Relationships

One-to-One (1:1): Each record in Table A is linked to only one record in Table B, and vice versa.
One-to-Many (1:M): A record in Table A can be linked to multiple records in Table B, but each record in Table B is linked to only one record in Table A.
Many-to-Many (M:N): Records in Table A can be linked to multiple records in Table B, and vice versa.

Example

One-to-one relationship:
- A person has one passport, a passport belongs to one person.
- Tables: Person and Passport

PersonID	Name	PassportID
1	Alice	101
2	Bob	102

PassportID	IssueDate
101	2020-01-01
102	2021-02-15

One-to-Many relationship:
- A teacher can have many students, but each student has only one teacher.
- Tables: Teacher and Student

TeacherID	Name
1	Mr. Smith
2	Ms. Johnson

StudentID	Name	TeacherID
101	Alice	1
102	Bob	1
103	Charlie	2

Many-to-many relationship:
- Students enroll in multiple courses, and courses have multiple students.
- Tables: Student, Course, and Enrollment (junction table)

StudentID	Name
101	Alice
102	Bob

CourseID	Title
201	Math
202	Science

StudentID	CourseID
101	201
101	202
102	201

How Relationships are Represented

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

1. System fundamentals2 subtopics

2. Computer organization1 subtopic

3. Networks1 subtopic

4. Computational thinking, problem-solving and programming3 subtopics

5. Abstract data structures (HL)1 subtopic

6. Resource management (HL)1 subtopic

7. Control (HL)1 subtopic

A. Databases4 subtopics

B. Modelling and simulation4 subtopics

C. Web science6 subtopics

D. Object-oriented programming (OOP)4 subtopics

IB Computer Science A.2.7 Relationships in Databases Notes

1. System fundamentals2 subtopics

2. Computer organization1 subtopic

3. Networks1 subtopic

4. Computational thinking, problem-solving and programming3 subtopics

5. Abstract data structures (HL)1 subtopic

6. Resource management (HL)1 subtopic

7. Control (HL)1 subtopic

A. Databases4 subtopics

B. Modelling and simulation4 subtopics

C. Web science6 subtopics

D. Object-oriented programming (OOP)4 subtopics

Mapped Relationships

How Relationships are Represented

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Mapped Relationships

How Relationships are Represented

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account