
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:
- Draw the Chen ERDs for this enterprise.
- Identify all possible relationships.
- Identify the connectivity for each relationship.
- Identify the dependencies for the relationships.
- Resolve all M: N relationships.

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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