Assume that “ABC media” has decided to have the relational schema for their database. Schema: 1. Video (videoCode, videoLength) 2. Model (modelNo, width, height, weight, depth, screenSize) 3. Site (siteCode, type, address, phone) 4. DigitalDisplay (serialNo, schedulerSystem, modelNo) Foreign key:modelNo references Model (modelNo) 5. Client (clientId, name, phone, address) 6. TechnicalSupport (empId, name, gender) 7. Administrator (empId, name, gender) 8. Salesman (empId, name, gender) 9. AirtimePackage (packageId, class, startDate, lastDate, frequency,videoCode) 10. AdmWorkHours (empId, day, hours)Foreign key: empId references Administrator (empId) 11. Broadcasts (videoCode, siteCode)Foreign key: videoCode references Video (videoCode)Foreign key: siteCode references Site (siteCode) 12. Administers (empId, siteCode)Foreign key: empId references Administrator (empId)Foreign key: siteCode references Site (siteCode) 13. Specializes (empId, modelNo)Foreign key: empId references TechnicalSupport (empId)Foreign key: modelNo references Model (modelNo) 14. Purchases (clientId, empId, packageId, commissionRate)Foreign key: clientId references Client (clientId)Foreign key: empId references Salesman (empId)Foreign key: packageId references AirtimePackage (packageId) 15. Locates (serialNo, siteCode)Foreign key: serialNo references DigitalDisplay (serialNo)Foreign key: siteCode references Site (siteCode Task: Given the above database schema, write Relational Algebra (RA) statements to answer the following question 8. Find the names of all employees (including administrators, salesmen, and technical supports) working in this company. So would number 8 look like this? I want to check my answer, if not tell me why and what the correct response is.    ∏name(Administrator) ∪ ∏name(Salesman) ∪ ∏name(TechnicalSupport)

Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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Assume that “ABC media” has decided to have the relational schema for their database.

Schema:

1. Video (videoCode, videoLength)

2. Model (modelNo, width, height, weight, depth, screenSize)

3. Site (siteCode, type, address, phone)

4. DigitalDisplay (serialNo, schedulerSystem, modelNo) Foreign key:modelNo references Model (modelNo)

5. Client (clientId, name, phone, address)

6. TechnicalSupport (empId, name, gender)

7. Administrator (empId, name, gender)

8. Salesman (empId, name, gender)

9. AirtimePackage (packageId, class, startDate, lastDate, frequency,videoCode)

10. AdmWorkHours (empId, day, hours)Foreign key: empId references Administrator (empId)

11. Broadcasts (videoCode, siteCode)Foreign key: videoCode references Video (videoCode)Foreign key: siteCode references Site (siteCode)

12. Administers (empId, siteCode)Foreign key: empId references Administrator (empId)Foreign key: siteCode references Site (siteCode)

13. Specializes (empId, modelNo)Foreign key: empId references TechnicalSupport (empId)Foreign key: modelNo references Model (modelNo)

14. Purchases (clientId, empId, packageId, commissionRate)Foreign key: clientId references Client (clientId)Foreign key: empId references Salesman (empId)Foreign key: packageId references AirtimePackage (packageId)

15. Locates (serialNo, siteCode)Foreign key: serialNo references DigitalDisplay (serialNo)Foreign key: siteCode references Site (siteCode

Task: Given the above database schema, write Relational Algebra (RA) statements to answer the
following question

8. Find the names of all employees (including administrators, salesmen, and technical
supports) working in this company.

So would number 8 look like this? I want to check my answer, if not tell me why and what the correct response is.   
∏name(Administrator) ∪ ∏name(Salesman) ∪ ∏name(TechnicalSupport)

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