Drawing using erd plus

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Exercises - ERD 1. A COMPANY, identified by CompanyID and described by CompanyName and Industry Type, is going to hire CONSULTANT's, identified by Consultants and described by Consultant Name, Consultant Skill (a consultant may have more than one skill). A consultant can work for only one company and a company hires one or more consultants. Draw an ERD. Now, redraw the ERD considering that each consultant can work for one or more companies and each company can have a contract with one or more consultants. Each time a consultant works for a company, a contract is written describing the terms for this consulting. The contract includes Contract_Date and Hourly_Rate. 2. The following illustrates the information about the "Bhawan Software Solutions". The company has several departments. Each department has a supervisor and a supervisor supervises only one department. Each department has at least one employee. Employees must be assigned to at least one, but possibly more departments. Each project has at least one employee working on it. An employee can work on many projects or may not assigned to any projects. The information to be stored about department includes the departmentID and name. The supervisor details to be stored include supervisorld, name. Employee details to be stored are Employeeld. name birthdate, age, gender, Date of joining and phone number. The information to be stored about project includes the projectID, name and duration Draw an E/R diagram using the above specifications. 3. Bahwan Dealership Company has an online system that store information about their EMPLOYEE's, CAR's, CUSTOMER's and INVOICE's. For each CAR the following information is stored: Car_ID to identify each car, Serial Number, and Model (which consists of ModelNo, Color and Year). For the CUSTOMER Customer(identifier), Name, Phone number, Address, City, and Country is stored. An EMPLOYEE identified by Emplo. Employee information like Name, Address, Qualification (some employees may have more than one qualification such as diploma, Master, PhD) is also stored in the database. An INVOICE is generated when a customer buy a car. The Invoice details are InvoicelD (identifier) and Date. The following are the business rules: 1. An employee may sell many cars or may not, but each car is sold by one and only one Employee. 2. A customer may buy one or more cars or may not, but each car is bought by only one customer. 3. An employee writes one or more invoices, but an invoice is written by one and only one employee. 4. A customer receives one or more invoices, but an invoice is issued to Minimum one and only one customer. 4. Define an ERD for the following narrative. The database for Real estate. . A home has a unique homeld, address and area. Address consists of street, city and state. An owner has a SSN, name, profession. Owner can have multiple professions. Every home can have exactly only one owner but an owner can have one or more homes. Agents are involved in the sale of a home. An agent can list one or many homes, but only one agent can list a home. An agent has a unique agent identifier, a name, and a phone number. A buyer entity type has a SSN, a name, a phone, and a price range. An agent can work with one or many buyers, but a buyer works with only one agent. 5. A university database contains information about professors, courses and semesters. . The professor entity has the attributes Social Security Number, name, Qualification (may have more than qualification). The course entity has the attributes courseid, coursename, contacthours. The semester entity has the attribute semid, year. Professors can teach for one or several semesters. Every semester should have atleast one professor as a teacher. Every professor teaches exactly one course. But if a professor is on leave he may not teach any course. And every course must be taught at least by one professor. Draw an ERD for the university database. Choose proper relations. Mention the minimum cardinalities. 6. Nobel Service is consultancy company providing consultancy services to small companies. Each company to which Nobel service is providing consultancy is called a PROJECT. It has several employees working in different shifts. The attributes of EMPLOYEE include Employee_ID(identifier), Name, Address, and Birthdate. Attributes of PROJECT include Project_ID(identifier), Project_Name, and Start_Date. Each employee may be assigned to one or more projects or may not be assigned to a project. A project must have at least one employee assigned and may have any number of employees assigned. An employee's billing rate may by project and the company wishes to record the applicable billing rate (Billing Rate) for each employee when assigned to a project