Below are a set of relational schema. Express each of queries listed below using

Question

Below are a set of relational schema. Express each of queries listed below using relational algebra. The operators that you will need are projection, selection, natural and theta joins, set union/intersection and set difference. Homeowner (ssn, name, address, occupation, martialstatus) House (address, price, numberofMortgagePaymentsDue, Developer) Developer (ssn, name, officeaddress, NumEmployees, AvgBasePriceToBuild) a) Find all the homeowners with the same name and that are married. (Assume each person has a unisex name). b) Find all the developers in the database that are also homeowners. c) Find all the homeowners with the same occupation that have only paid at least five of their mortgage payments. d) Find all the homeowners and developers who live in the same house. (There might be a group of people who live in House A and another that live in House B, so essentially the answer should be a set of sets).

Explanation / Answer

a)

ssn,name,address,occupation,maritalstatu ( maritalstatus= ‘married’ and Homeowner.name=Homeowner.name (Homeowner X Homeowner))

b)

Homeowner.ssn=Developer.ssn(Developer|X|Homeowner)

c)

ssn,name (Homeowner.occupation=(Homeowner.occupation(Homeowner)(Homeowner))

d)

Homeowner.name,Developers.name,Homeowner.address(Homeowner.address=Homeowner.address and Homeowner.ssnHomeowner.ssn and Homeowner.ssn=Developer.ssn( Homeowner U Developers))

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