3. A relational database as follows: suppose that the teaching database includes four relations: teacher relation T(T#, Tname , Title), with attributes teacher number, teacher name and professional Title;relation c(c#, cname , T# ), with attributes the course number, course name and teacher number of the course; student relation S (S#, Firstname , Lastname, Age, Sex) with student number, name and gender ; course selection relation SC (S#, c#, score) with attributes the student number, course number and Score. Assuming that the corresponding data has been stored in each table