Index: iknow-api/Repository/Interface/IProfRepository.cs
===================================================================
--- iknow-api/Repository/Interface/IProfRepository.cs	(revision 1b20b226a74790f84dc06dc488f4f761b510a3f2)
+++ iknow-api/Repository/Interface/IProfRepository.cs	(revision 1b20b226a74790f84dc06dc488f4f761b510a3f2)
@@ -0,0 +1,26 @@
+using iknow_api.Models;
+
+namespace iknow_api.Repositories
+{
+    public interface IProfRepository
+    {
+        /// <summary>
+        /// Every semester-subject row taught by this professor, with the
+        /// enrolment, student, subject, semester and grade loaded.
+        /// </summary>
+        Task<List<SemesterSubject>> GetTaughtSemesterSubjectsAsync(int professorId);
+
+        /// <summary>
+        /// The semester-subject row this professor teaches for one student and
+        /// subject. When a student has taken the subject more than once, the
+        /// most recent enrolment wins. Null when the professor does not teach
+        /// that student in that subject.
+        /// </summary>
+        Task<SemesterSubject?> FindTaughtSemesterSubjectAsync(int professorId, int studentId, int subjectId);
+
+        Task<PassedSubject?> GetPassedSubjectAsync(int semesterSubjectId);
+        Task AddPassedSubjectAsync(PassedSubject passed);
+        Task UpdatePassedSubjectAsync(PassedSubject passed);
+        Task RemovePassedSubjectAsync(PassedSubject passed);
+    }
+}