Exercise Consider the following relational database: STUDENT (STDNO, SNAME, DEPTNO#) DEP (DEPTNO, DNAME) COURSE (CORSNO, CNAME, DEPTNO#, CMAX) ENROLMENT (STDNO# CORSNO#, GRADE, EDATE) STUDENT.DEPTNO is the department number of the student. COURSE.DEPTNO is the department number that offers the course. ENROLMENT models the registrations of students in courses (M:M relationship) where the GRADE is the grade obtained by the student in the course. PART I: DATA DESCRIPTION LANGUAGE (DDL) 1) Write DDL commands to create the four tables without any constraint. Nom de colonne Signification Type Size STDNO Student Number Number 8 SNAME Student name Varchar2 30 DEPTNO Department Number Varchar2 2 DNAME Department name Varchar2 20 CORSNO Course Number Number 3 CNAME Course Name Varchar2 30 CMAX Max. students allowed Number 2 GRADE Obtained Grade Number 2 EDATE Enrolment date Date 2) Add all the following constraints: - Primary Key Foreign Key Constraints on the STUDENT table: - Sname: Not Null - Each student must belong to a department Constraint on the ENROLMENT table *- Edate: have a default value equal to the system date