Consider the following PL/SQL script: SET SERVEROUTPUT ON BEGIN INSERT INTO COURSE (course_no, description, created_by, created-date, modified_by, modified_date) VALUES (course_no_seq.nextval, 'database development', USER, SYSDATE); COMMIT DBMS_OUTPUT.PUT_LINE ("one course has been added' ); END; Assumptions: All the COURSE table fields have check constraints defined on them indicating that none can be null. 1. Explain why the script does not execute successfully. 2. Add a user-defined exception to the script, so that the error generated by the INSERT statement is handled. Assign the code 2290 to this exception.