relational algebra question

[conorhegarty18]

hi please please help with this question ive been on for hours...

Q. Find the details of all patients that have shared any doctors with the patient that has the code “P555".

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

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

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

Is_Seen_By (PatientCode, DoctorCode, Date, Time).

[Island1]

Could you give a little more detail as to what you see as the outcome of this question? Are you asking how to write a query using these table (I think) layouts, or what?

Get back with a more detailed description of your need, and I'm sure we can help you further.

Thanks!

Bill

[conorhegarty18]

at the min this is the answer which i have came to! i am not sure if this is in fact correct...

4. Find the details of all patients that have shared any doctors with the patient that has the code “P555".

Rel 1 = SELECT FROM Is_Seen_By WHERE PatientCode = P555
Rel 2 = Operation NATJOIN Rel 1 with DoctorCode Common
Rel 3 = PatientNATJOIN Rel2 with PatientCode Common

thanks