PL/SQL Program to Check if Number is Prime

Here is a simple PL/SQL program that you can use to check if a number is prime:

declare
  -- Declare a variable to hold the number
  num number := 5;

  -- Declare a variable to hold the result
  is_prime boolean := true;
begin
  -- Check if the number is less than 2
  if num < 2 then
    is_prime := false;
  else
    -- Check if the number is divisible by any number between 2 and the square root of the number
    for i in 2..sqrt(num) loop
      if mod(num, i) = 0 then
        is_prime := false;
        exit;
      end if;
    end loop;
  end if;

  -- Print the result
  if is_prime then
    dbms_output.put_line('Number is prime.');
  else
    dbms_output.put_line('Number is not prime.');
  end if;
end;
/

Output:

Number is prime.

Certainly! Here's a brief explanation of how the above PL/SQL program works:

1. The program begins by declaring a variable num to hold the input number, and a variable is_prime to hold the result of the check.
2. The program then checks if the number is less than 2. If it is, then it sets is_prime to false and ends the check, since numbers less than 2 are not considered prime.
3. If the number is greater than or equal to 2, the program enters a loop that iterates over the numbers between 2 and the square root of the number. This is because it is not necessary to check numbers greater than the square root of the number, since they will not be divisible by the number.
4. Within the loop, the program checks if the number is divisible by the current loop variable (using the mod function). If it is, then it sets is_prime to false and exits the loop.
5. If the loop completes without finding a divisor, then is_prime remains true. The program then prints the value of is_prime, indicating whether the number is prime or not.

Here is another example of PL/SQL program to print prime numbers from 1 to 100.

PL/SQL program to print prime numbers from 1 to 100

declare
  -- Declare a variable to hold the current number
  num number := 1;
  is_prime boolean;
begin
  -- Loop over the numbers from 1 to 100
  while num <= 100 loop
    is_prime := true;
    -- Check if the number is less than 2
    if num < 2 then
      is_prime := false;
    else
      -- Check if the number is divisible by any number between 2 and the square root of the number
      for i in 2..sqrt(num) loop
        if mod(num, i) = 0 then
          is_prime := false;
          exit;
        end if;
      end loop;
    end if;

    -- If the number is prime, print it
    if is_prime then
      dbms_output.put_line(num);
    end if;

    -- Increment the number
    num := num + 1;
  end loop;
end;
/

Output:

2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
59
61
67
71
73
79
83
89
97