Question 3 from books homework

DECLARE
    /*
        Create new cursor.
        We use 'r_date is null' to check for book state
        r_date is null     = not returned yet
        r_date is not null = returned already
    */
    CURSOR bk_c IS
        SELECT * FROM borrow
        WHERE r_date IS NULL;

    /* Declare a new record for our cursor */
    bk_rec bk_c%ROWTYPE;

    /* Assuming the current date is 10th of November */
    /* You should use sysdate for real application */
    crnt_date borrow.r_date%TYPE := TO_DATE('10-NOV-18');

    /* Declare member's name and mobile variables */
    mem_name member.name%TYPE;
    mem_mobile member.mobile%TYPE;

    days_since_borrowed NUMBER;
BEGIN

    /* Open cursor and loop through result */
    OPEN bk_c;
    LOOP
        /* Fetch result into our record */
        FETCH bk_c INTO bk_rec;
        /* Exit loop if no result found */
        EXIT WHEN bk_c%notfound;

        /* Find out member name and mobile */
        SELECT name, mobile INTO mem_name, mem_mobile
        FROM member WHERE m_id = bk_rec.m_id;

        /*
            Calculate how many days since the book borrowed
            By subtracting the borrow date from current date
            Use FLOOR to avoid decimals.
        */
        days_since_borrowed := FLOOR(crnt_date - bk_rec.b_date);

        /* Print result */
        dbms_output.put_line(mem_name || ' ' || mem_mobile ||
            ' has not returned his book since '
            || days_since_borrowed || ' days.');

    END LOOP;

    CLOSE bk_c;
END;
/