Database System Concepts
Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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Can you tell me if there is any mistakes in this diagram??

thats its requirenments:

During peak periods, Temporary Employment Corporation (TEC) places temporary workers in companies. TEC’s manager gives you the following description of the business:

 

  • TEC has a file of candidates who are willing to work.

  • If the candidate has worked before, that candidate has a specific job history. (Naturally, no job history exists if the candidate has never worked.) Each time the candidate works, one additional job history record is created.

  • Each candidate has earned several qualifications. Each qualification may be earned by more than one candidate. (For example, it is possible for more than one candidate to have earned a BBA degree or a Microsoft Network Certification. And clearly, a candidate may have earned both a BBA and a Microsoft Network Certification.)

  • TEC offers courses to help candidates improve their qualifications.

  • Every course develops one specific qualification; however, TEC does not offer a course for every qualification. Some qualifications have multiple courses that develop that qualification. 

  • Some courses cover advanced topics that require specific qualifications as prerequisites. Some courses cover basic topics that do not require any prerequisite qualifications.  A course can have several prerequisites.  A qualification can be a prerequisite for more than one course.

  • Courses are taught during training sessions. A training session is the presentation of a single course.  Over time, TEC will offer many training sessions for each course; however, new courses may not have any training sessions scheduled right away.

  • Candidates can pay a fee to attend a training session. A training session can accommodate several candidates, although new training sessions will not have any candidates registered at first. 

  • TEC also has a list of companies that request temporaries.

  • Each time a company requests a temporary employee, TEC makes an entry in the Openings folder. That folder contains an opening number, a company name, required qualifications, a starting date, and anticipated ending date, and hourly pay.

  • Each opening requires only one specific or main qualification.

  • When a candidate matches the qualification, the job is assigned, and an entry is made in the Placement Record folder. That folder contains an opening number, a candidate number, the total hours worked, etc. In addition, an entry is made in the job history for the candidate.

  • An opening can be filled by many candidates, and a candidate can fill many openings.

  • TEC uses special codes to describe a candidate’s qualifications for an opening.

 

TEC’s management wants to keep track of the following entities:

  • COMPANY
  • OPENING
  • QUALIFICATION
  • CANDIDATE
  • JOB_HISTORY
  • PLACEMENT
  • COURSE
  • SESSION

 

Given that information, do the following:

  1. Draw the Chen ERDs for this enterprise.
  2. Identify all possible relationships.
  3. Identify the connectivity for each relationship.
  4. Identify the dependencies for the relationships.
  5. Resolve all M: N relationships.
# Entity-Relationship Diagram (ERD) Overview

This Entity-Relationship Diagram (ERD) illustrates the relationships between various entities in a job placement context. Understanding this diagram is fundamental for designing databases related to human resource management, job placements, and educational courses offered to candidates. Below is a detailed explanation of each entity, relationship, and attribute used in this ERD:

## Entities:
1. **CANDIDATE**:
   - Represents individuals looking for job opportunities.
   
2. **OPENING**:
   - Represents job openings or vacancies within companies.
   - Attributes: `companyName`, `openingNum`, `requiredQual`

3. **COURSE**:
   - Represents educational courses available for candidates.
   
4. **SESSION**:
   - Represents different sessions for courses.
    
5. **QUALIFICATION**:
   - Represents the qualifications or certifications a candidate can earn.
   
6. **JOB_HISTORY**:
   - Represents the past job positions held by candidates.

7. **PLACEMENT**:
   - Represents placement records indicating the job openings filled by candidates.
   - Attributes: `openingNum`, `totalHrsWorked`, `candidateNum`

8. **COMPANY**:
   - Represents the companies offering job opportunities.
   
## Relationships:
1. **DESCRIBE**:
   - A candidate can have multiple qualifications.
   - Relationship between `CANDIDATE` and `QUALIFICATION`:
     - Many-to-Many (M:N) Relationship.

2. **FILL**:
   - Candidates fill job openings.
   - Relationship between `CANDIDATE` and `OPENING`:
     - Many-to-Many (M:N) Relationship.

3. **REQUIRE**:
   - Job openings may require specific qualifications.
   - Relationship between `OPENING` and `QUALIFICATION`:
     - One-to-One (1:1) Relationship.

4. **MADE**:
   - Represents job histories made by candidates.
   - Relationship between `CANDIDATE` and `JOB_HISTORY`:
     - One-to-One (1:1) Relationship.

5. **OPENS**:
   - Job openings create placements.
   - Relationship between `OPENING` and `PLACEMENT`:
     - One-to-Many (1:N) Relationship.

6. **HAS**:
   - Courses have multiple sessions.
   - Relationship between `COURSE` and `SESSION`:
     - One
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Transcribed Image Text:# Entity-Relationship Diagram (ERD) Overview This Entity-Relationship Diagram (ERD) illustrates the relationships between various entities in a job placement context. Understanding this diagram is fundamental for designing databases related to human resource management, job placements, and educational courses offered to candidates. Below is a detailed explanation of each entity, relationship, and attribute used in this ERD: ## Entities: 1. **CANDIDATE**: - Represents individuals looking for job opportunities. 2. **OPENING**: - Represents job openings or vacancies within companies. - Attributes: `companyName`, `openingNum`, `requiredQual` 3. **COURSE**: - Represents educational courses available for candidates. 4. **SESSION**: - Represents different sessions for courses. 5. **QUALIFICATION**: - Represents the qualifications or certifications a candidate can earn. 6. **JOB_HISTORY**: - Represents the past job positions held by candidates. 7. **PLACEMENT**: - Represents placement records indicating the job openings filled by candidates. - Attributes: `openingNum`, `totalHrsWorked`, `candidateNum` 8. **COMPANY**: - Represents the companies offering job opportunities. ## Relationships: 1. **DESCRIBE**: - A candidate can have multiple qualifications. - Relationship between `CANDIDATE` and `QUALIFICATION`: - Many-to-Many (M:N) Relationship. 2. **FILL**: - Candidates fill job openings. - Relationship between `CANDIDATE` and `OPENING`: - Many-to-Many (M:N) Relationship. 3. **REQUIRE**: - Job openings may require specific qualifications. - Relationship between `OPENING` and `QUALIFICATION`: - One-to-One (1:1) Relationship. 4. **MADE**: - Represents job histories made by candidates. - Relationship between `CANDIDATE` and `JOB_HISTORY`: - One-to-One (1:1) Relationship. 5. **OPENS**: - Job openings create placements. - Relationship between `OPENING` and `PLACEMENT`: - One-to-Many (1:N) Relationship. 6. **HAS**: - Courses have multiple sessions. - Relationship between `COURSE` and `SESSION`: - One
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