database systems

Homework2 Suppose we have 3 tables which are Users, Videos and Ratings. Each user has a useriD (primary key) and name. Each video has a videolD(primary key), uploader (UserID ... Foreign key), length(seconds), and title. Each vedio (UserID + VideolD) is given a rating from 1 to 5 . Table 1: Users Table 2: Videos Table 3 : Ratings 3. write math expression for the following query ( 3 points) Query: selects the uploader of all videos under 20 seconds