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, an 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. The list of codes is shown in Table P4.10.
TABLE P4.10 TEC QUALIFICATION CODES
CODEDESCRIPTION
SEC-45Secretarial work, at least 45 words per minute
SEC-60Secretarial work, at least 60 words per minute
CLERKGeneral clerking work
PRG-VBProgrammer, Visual Basic
PRG-C++Programmer, C++
DBA-ORADatabase Administrator, Oracle
DBA-DB2Database Administrator, IBM DB2
DBA-SQLSERVDatabase Administrator, MS SQL Server
SYS-1Systems Analyst, level 1
SYS-2Systems Analyst, level 2
NW-NOVNetwork Administrator, Novell experience
WD-CFWeb Developer, ColdFusion
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:
a. Draw the Crow’s Foot ERDs for this enterprise.
b. Identify all possible relationships.
c. Identify the connectivity for each relationship.
d. Identify the mandatory/optional dependencies for the relationships.
e. Resolve all M:N relationships.