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I'm new to this and have been given a database. I've been asked to write a Basic relational algebra formula which collects failed test results with a certain teacher and display the surname and code of the student.

STUDENT (StudentSurName, StudentCode)

TEACHER (TeacherName)

TEST (Result)

π StudentSurName,StudentCode (σ Result = "fail"(σ TeacherName = "Mr Willis"))

Can anyone help and point out where I am going wrong ?

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Should be:

π StudentSurName,StudentCode (σ Result="fail" Test (σ TeacherName="Mr Willis" Teacher))

But even then it will not give a usable result since there is no relation between the STUDENT, TEACHER, and TEST. Who's result it is? Who gave the result?

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