1. Consider the design of a database for a web site of youtube videos for comedy standup shows, in which each youtube is exactly for one comedian. Each youtube video is identified by a unique URL (such as https://youtu.be/buSv1jjAels), a title and a description of the youtube, the date on which the youtube is posted, and a list of tags (each tag is a single word in lower cases). A registered user can search for youtube videos by the name of a comedian or by the tags of videos, using a text field like the one used by google.com, and then click any youtube link in the result list to play that youtube video. Each comedian has a first name, a last name, a birthday, and a birthplace. Moreover, registered users can post and comment on these youtubes. Each registered user is identified by a unique username, which must be an email, a password, a first name, a last name, the gender, and his/her age. A registered user can give at most one review for each youtube video, but on a particular day, the user can post at most five youtube videos. The review given by a user has a score of {"Poor", "Fair", "Good", "Excellent"} and then a short remark. A user can also modify an existing review as well as deleting an existing review. Each user has a favorite list of comedians. Each user can insert and delete a comedian from that favorite list. A new comedian can be added to a list when the user is watching a comedian's video that interests him/her by clicking the "Add to favorite comedians" button. The system has a distinguished user called "root" whose username is root (this is the only username that is not an email). • Draw an E-R diagram for the system, in particular, use arrows or thick lines to represent constraints appropriately. Write down your assumptions and justifications briefly and clearly. • Translate the above E-R diagram into a relational model, i.e., write a set of CREATE TABLE statements. In particular, specify primary key, foreign key and other constraints whenever possible.