Решение проблемы:
SELECT DISTINCT StatementID, StatementNumber, FlagMain, StudentID, DateCreate, MarkValue, AcademHours, teacher1ID, teacher2ID, teacher3ID, WorkLPSubjects.WorkLPSubjectID
FROM [Statement] JOIN WorkLPSubjects
ON [Statement].WorkLPSubjectID = WorkLPSubjects.WorkLPSubjectID
JOIN BaseLearningPlan
ON WorkLPSubjects.BaseLearningPlanID = BaseLearningPlan.BaseLearningPlanID
JOIN SpecialtyInfo
ON BaseLearningPlan.SpecialtyID = SpecialtyInfo.specialtyID
JOIN FacultyInfo
ON SpecialtyInfo.FacultyID = FacultyInfo.FacultyID
JOIN UsersBD
ON FacultyInfo.FacultyID = UsersBD.FacultID
WHERE UsersID = 20