Example
Loop FOR works on similar rules as other loops. FOR loop is executed exact number of times and this number is known at the beginning - lower and upper limits are directly set in code. In every step in this example, loop is increment by 1.
Simple example:
DECLARE
v_counter NUMBER(2); --declaration of counter variable
BEGIN
v_counter := 0; --point of start, first value of our iteration, execute of variable
FOR v_counter IN 1..10 LOOP --The point, where lower and upper point of loop statement is declared - in this example, loop will be executed 10 times, start with value of 1
dbms_output.put_line('Current iteration of loop is ' || v_counter); --show current iteration number in dbms script output
END LOOP; --end of loop declaration
END;
And the result is:
Current iteration of loop is 1
Current iteration of loop is 2
Current iteration of loop is 3
Current iteration of loop is 4
Current iteration of loop is 5
Current iteration of loop is 6
Current iteration of loop is 7
Current iteration of loop is 8
Current iteration of loop is 9
Current iteration of loop is 10
Loop FOR has additional property, which is working in reverse. Using additional word 'REVERSE' in declaration of lower and upper limit of loop allow to do that. Every execution of loop decrement value of v_counter by 1.
Example:
DECLARE
v_counter NUMBER(2); --declaration of counter variable
BEGIN
v_counter := 0; --point of start
FOR v_counter IN REVERSE 1..10 LOOP
dbms_output.put_line('Current iteration of loop is ' || v_counter); --show current iteration number in dbms script output
END LOOP; --end of loop declaration
END;
And the result:
Current iteration of loop is 10
Current iteration of loop is 9
Current iteration of loop is 8
Current iteration of loop is 7
Current iteration of loop is 6
Current iteration of loop is 5
Current iteration of loop is 4
Current iteration of loop is 3
Current iteration of loop is 2
Current iteration of loop is 1
