PL/SQL Program for Fibonacci Series

The Fibonacci series is a famous mathematical sequence where each new number is the sum of the two preceding ones. Writing a program to generate this sequence is a fantastic exercise for learning how to manage and "shift" variable values inside a loop.

The sequence always starts with 0 and 1. 0, 1, 1, 2, 3, 5, 8, 13, 21, ...

This simple guide will show you the logic and a complete PL/SQL program to generate this series.

What You Need to Know

To write this program, you will use a few basic PL/SQL concepts:

1. Enabling Output: You must run this command once in your SQL tool to see the printed results:SET SERVEROUTPUT ON;
2. Anonymous Block: We will write our code in a DECLARE...BEGIN...END; block.
3. Variables: This is the most important part. We need:
   • n_limit: How many terms of the series to print (e.g., 10).
   • n1: The first number in the sequence, initialized to 0.
   • n2: The second number in the sequence, initialized to 1.
   • n_temp: A temporary variable to hold the new sum during our calculation.
4. FOR Loop: We will use a loop to calculate each new term, starting from the third term up to our limit.

PL/SQL Program: Print the Fibonacci Series

This program will print the first n_limit terms of the Fibonacci series.

PL/SQL Program

SET SERVEROUTPUT ON;

DECLARE
  -- How many terms of the series to print
  n_limit NUMBER := 10; 
  
  -- Initialize the first two numbers of the series
  n1 NUMBER := 0;
  n2 NUMBER := 1;
  
  -- A temporary variable for swapping
  n_temp NUMBER;

BEGIN

  -- Handle edge cases
  IF n_limit < 1 THEN
    RETURN; -- Do nothing if the limit is less than 1
  END IF;

  -- 1. Print the first number (0)
  DBMS_OUTPUT.PUT_LINE(n1); 
  
  -- 2. Loop from the 2nd term up to the limit
  FOR i IN 2..n_limit LOOP
  
    -- Print the next number in the series (starts with 1)
    DBMS_OUTPUT.PUT_LINE(n2);
    
    -- 3. Calculate the *next* term (0 + 1 = 1)
    n_temp := n1 + n2;
    
    -- 4. "Shift" the numbers for the next iteration
    n1 := n2;      -- The 1st number becomes the 2nd number
    n2 := n_temp;  -- The 2nd number becomes the new sum
    
  END LOOP;

END;
/

Result (for n_limit := 10)

0
1
1
2
3
5
8
13
21
34

Program Explanation

1. DECLARE section: We set our limit n_limit to 10. We initialize n1 to 0 and n2 to 1, which are the two "seed" values of the series.
2. BEGIN section: The logic starts.
3. IF n_limit < 1 THEN ...: A quick check to make sure we don't try to run the loop.
4. DBMS_OUTPUT.PUT_LINE(n1);: Before the loop starts, we print the very first number, 0.
5. FOR i IN 2..n_limit LOOP: We start a loop that will run from i=2 up to i=10 (9 times) to generate the rest of the terms.

Inside the loop (the "shifting" logic):

• Loop 1 (i=2):
  • DBMS_OUTPUT.PUT_LINE(n2); -> Prints 1
  • n_temp := n1 + n2; -> n_temp := 0 + 1 = 1
  • n1 := n2; -> n1 is now 1
  • n2 := n_temp; -> n2 is now 1
• Loop 2 (i=3):
  • DBMS_OUTPUT.PUT_LINE(n2); -> Prints 1
  • n_temp := n1 + n2; -> n_temp := 1 + 1 = 2
  • n1 := n2; -> n1 is now 1
  • n2 := n_temp; -> n2 is now 2
• Loop 3 (i=4):
  • DBMS_OUTPUT.PUT_LINE(n2); -> Prints 2
  • n_temp := n1 + n2; -> n_temp := 1 + 2 = 3
  • n1 := n2; -> n1 is now 2
  • n2 := n_temp; -> n2 is now 3
• Loop 4 (i=5):
  • DBMS_OUTPUT.PUT_LINE(n2); -> Prints 3
  • n_temp := n1 + n2; -> n_temp := 2 + 3 = 5
  • n1 := n2; -> n1 is now 3
  • n2 := n_temp; -> n2 is now 5

This process continues until the loop finishes, with n1 and n2 always holding the two most recent numbers in the series.