Relational algebra help?!

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Published on 2011-01-12T23:49:06Z Indexed on 2011/01/12 23:53 UTC
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im new to relational algebra and finding it difficult. Ive answered a few questions, however they where relatively simple. Could do with help with these though.

Database
Patient (PatientCode, PatientSurname, PatientFirstname, PatientSex, PatientAge, PatientOccupation, PatientHeight, PatientWeight, PatientAddress) 

Doctor (DoctorCode, DoctorSurName,  DoctorFirstName, DoctorPrivateAddress, MobileNo, Doctor Specilisim) 

Operation (Operation Code, PatientCode, DoctorCode, Date, Time, Result, OperationType) 

Is_Seen_By (PatientCode, DoctorCode, Date, Time).

Q1. Find the surname and gender of the patients that have been operated on by doctor "DR333" and results have not been successful.

Q2. Find the code of the operations that have been done on the 18th of November 2010 and have been successful, please also list the name of the doctors which were involved with the operation.

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