/*
** This code accumulates 100 units of part number 9999 from
** various storage bins.
*/
DECLARE
    CURSOR bin_cur(part_number NUMBER) IS SELECT amt_in_bin
        FROM bins
        WHERE part_num = part_number AND 
            amt_in_bin > 0
            ORDER BY bin_num
            FOR UPDATE OF amt_in_bin;
    bin_amt         bins.amt_in_bin%TYPE;
    total_so_far    NUMBER(5) := 0;
    amount_needed   CONSTANT NUMBER(5) := 100;
    bins_looked_at  NUMBER(3) := 0;
BEGIN
    OPEN bin_cur(9999);
    WHILE total_so_far < amount_needed LOOP
        FETCH bin_cur INTO bin_amt;
        EXIT WHEN bin_cur%NOTFOUND;
             /* If we exit, there's not enough to *
              * satisfy the order.                */
        bins_looked_at := bins_looked_at + 1;
        IF total_so_far + bin_amt < amount_needed THEN
            UPDATE bins SET amt_in_bin = 0
                WHERE CURRENT OF bin_cur;  
                    -- take everything in the bin
            total_so_far := total_so_far + bin_amt;
        ELSE        -- we finally have enough
            UPDATE bins SET amt_in_bin = amt_in_bin
                - (amount_needed - total_so_far)
                WHERE CURRENT OF bin_cur;
            total_so_far := amount_needed;
        END IF;
    END LOOP;
    CLOSE bin_cur;
    INSERT INTO temp VALUES (NULL, bins_looked_at, '<- bins looked at');
    COMMIT;
END;
/