FOR Loops

Structure:

[label] FOR loop_counter IN [REVERSE] lower_bound..upper_bound LOOP
    group_of_statements
END LOOP [label];

Lower/upper bounds are inclusive. Counter is implicitly initialized as PLS_INTEGER.

Example:

DECLARE
    l_sum NUMBER := 0;
BEGIN
    FOR l_counter IN 1..3 LOOP
        l_sum := l_sum + l_counter;
    END LOOP;
END;

Can use literals, variables, or expressions for loop bounds:

DECLARE
    l_lower NUMBER := 2;
    l_upper NUMBER := 5;
BEGIN
    FOR l_counter in l_lower..(l_upper/l_lower) LOOP
        dbms_output.PUT_LINE(l_counter);
    END LOOP;
END;

To increment using a different step size:

DECLARE
    l_step_counter NUMBER;
BEGIN
    FOR l_counter in 1..3 LOOP
        l_step_counter := l_counter * 2;
    END LOOP;
END;

Example using count():

CREATE TABLE departments(
    dept_id NUMBER NOT NULL PRIMARY KEY,
    dept_name VARCHAR2(60));

INSERT INTO departments (dept_id, dept_name) values (1, 'Sales');
INSERT INTO departments (dept_id, dept_name) values (2, 'IT');

DECLARE
    l_dept_count NUMBER;
BEGIN
    SELECT count(*)
        INTO l_dept_count
            FROM departments;
    FOR l_counter IN 1..l_dept_count LOOP
        dbms_output.PUT_LINE(l_counter);
    END LOOP;
END;