1. Add a table-level PRIMARY KEY constraint to the EMP table on the ID column. The constraint should be named at creation. Name the constraint my_emp_id_pk ALTER TABLE emp ADD CONSTRAINT my_emp_id_pk PRIMARY KEY (id); 2. Create a PRIMARY KEY constraint to the DEPT table using the ID column. The constraint should be named at creation. Name the constraint my_dept_id_pk. ALTER TABLE dept ADD CONSTRAINT my_dept_id_pk PRIMARY KEY(id); 3. Add a column DEPT_ID to the EMP table. Add a foreign key reference on the EMP table that ensures that the employee is not assigned to a nonexistent department. Name the constraint my_emp_dept_id_fk. ALTER TABLE emp ADD (dept_id NUMBER(7)); ALTER TABLE emp ADD CONSTRAINT my_emp_dept_id_fk FOREIGN KEY (dept_id) REFERENCES dept(id); 4. Confirm that the constraints were added by querying the USER_CONSTRAINTS view. Note the types and names of the constraints. Save your statement text in a file called lab10_4.sql. SELECT constraint_name, constraint_type FROM user_constraints WHERE table_name IN (’EMP’, ’DEPT’); 5. Display the object names and types from the USER_OBJECTS data dictionary view for the EMP and DEPT tables. Notice that the new tables and a new index were created. SELECT object_name, object_type FROM user_objects WHERE object_name LIKE ’EMP%’ OR object_name LIKE ’DEPT%’;If you have time, complete the following exercise: 6. Modify the EMP table. Add a COMMISSION column of NUMBER data type, precision 2, scale 2. Add a constraint to the commission column that ensures that a commission value is greater than zero. ALTER TABLE EMP ADD commission NUMBER(2,2) CONSTRAINT my_emp_comm_ck CHECK (commission >= 0;