Refactor code without cursor PL/SQL - oracle

Question

How can I refactor these lines of code without using CURSOR?
I am beginner in PL/SQL.
Any help would be appreciated. Thank you
DECLARE
CURSOR c_emps IS
SELECT employee_id
FROM bonus;
v_region HR.REGIONS.region_name%TYPE;
v_salary hr.employees.salary%TYPE;
BEGIN
FOR r_emps IN c_emps LOOP
SELECT reg.region_name, emp.salary
INTO v_region, v_salary
FROM hr.employees emp,
hr.departments dep,
hr.Locations loc,
hr.countries cot,
hr.regions reg
WHERE emp.department_id = dep.department_id AND
dep.location_id = loc.location_id AND
loc.country_id = cot.country_id AND
cot.region_id = reg.region_id AND
employee_id = r_emps.employee_id;
IF v_region = 'Europe' THEN
UPDATE bonus
SET bonus = bonus + (v_salary * .01)
WHERE employee_id = r_emps.employee_id;
ELSE
UPDATE bonus
SET bonus = v_salary * .01
WHERE employee_id = r_emps.employee_id;
END IF;
END LOOP;
COMMIT;
END;
/

Answer 1

CURSOR c_emps IS
SELECT employee_id
FROM bonus;
You don't need to explicitly declare the CURSOR. You could do it in the CURSOR FOR LOOP itself:
FOR r_emps IN (SELECT employee_id FROM bonus)
LOOP
If PL/SQL is not mandatory, then you could do it in plain SQL using CASE expression in the UPDATE statement.
Something like,
UPDATE bonus
SET bonus =
CASE
WHEN region = 'Europe'
THEN bonus + (v_salary * .01)
ELSE v_salary * .01
...
and so on
Yes, you need to rewrite the entire PL/SQL code into a SQL update statement. But, it would be much better and faster. For loop is row-by-row processing, thus it is slow-by-slow. Avoid PL/SQL if you could do the same in SQL.

Answer 2

When working with SQL Server, an awful lot of effort is taken to avoid cursors because they are handled very poorly. Using a cursor in SQL Server is like slogging waist-deep through molasses. Oracle handles cursors much better so you see a lot more row-by-row work in Oracle. Too much, really. Even in Oracle, if something can be done with a single SQL statement, it is far superior than using PL/SQL cursors and looping.
Unfortunately, Oracle doesn't allow joins in UPDATE statements. But not to worry, the more recent innovation, the MERGE statement does.
MERGE INTO BONUS B
USING(
SELECT EMP.EMPLOYEE_ID, EMP.SALARY, REG.REGION_NAME
FROM HR.EMPLOYEES EMP
JOIN HR.DEPARTMENTS DEP
ON DEP.DEPARTMENT_ID = EMP.DEPARTMENT_ID
JOIN HR.LOCATIONS LOC
ON LOC.LOCATION_ID = DEP.LOCATION_ID
JOIN HR.COUNTRIES COT
ON COT.COUNTRY_ID = LOC.COUNTRY_ID
JOIN HR.REGIONS REG
ON REG.REGION_ID = COT.REGION_ID ) U
ON( U.EMPLOYEE_ID = b.EMPLOYEE_ID )
WHEN MATCHED THEN
UPDATE SET B.BONUS =( u.SALARY * 0.01 ) +
CASE U.REGION_NAME WHEN 'Europe' THEN B.BONUS ELSE 0 END;
How nice that the when not matched clause is not required, effectively turning the merge into a very flexible update.