Exercise Consider the following relational database: STUDENT (STDNO, SNAME, DEPTNO#) DEP (DEPTNO, ONAME) 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. PARTI: DATA DESCRIPTION LANGUAGE (DDL) 1) Write DDL commands to create the four tables without any constraint. Nom de Signification Type Size colonne STONO Student Number Number SNAME Student Varchar2 30 name DEPTNO Department Varchar2 Number DNAME Department Varchar2 name CORSNO Course Number Number CNAME Course Name Varchar2 30 CMAX Max. Number 2 students allowed GRADE Obtained Number Grade EDATE Enrolment Date date 8 2 20 3 2 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