mysql - 创建并调用 MYSQL 函数以查找斐波那契数直到 n 个数

Question

我的方法

DELIMITER $$
CREATE FUNCTION fibonacci(num INT)
RETURNS INT
DETERMINISTIC
BEGIN
    DECLARE fib1 INT DEFAULT 0;
    DECLARE fib2 INT DEFAULT 1;
    DECLARE fib3 INT DEFAULT 0;
    DECLARE str VARCHAR(255) DEFAULT '01';
    
    IF num = 1 THEN
        RETURN fib1;
    ELSEIF num = 2 THEN
        RETURN CONCAT(fib1, fib2);
    ELSE
        WHILE num > 2 DO
            SET fib3 = fib1 + fib2;
            SET fib1 = fib2;
            SET fib2 = fib3;
            SET num = num - 1;
            SET str = CONCAT(str, fib3);
        END WHILE;
        RETURN str;
    END IF;
END $$
DELIMITER ;

如果我使用 SELECT fibonacci(6) 调用上述函数；它返回没有前导零（0）的 11235。我怎样才能显示前导零？

Answer 1

我想它会帮助你

DELIMITER $$
CREATE FUNCTION fibonacci_number(n INT) RETURNS INT
DETERMINISTIC
BEGIN
    DECLARE f_0 INT default 0;
    DECLARE f_1 INT DEFAULT 1;
    DECLARE out_fib INT;
    DECLARE i INT;
    DECLARE f_2 INT;

    SET f_0 = 0;
    SET f_1 = 1;
    SET i = 1;

    WHILE (i<=n) DO
        SET f_2 = f_0 + f_1;
        SET f_0 = f_1;
        SET f_1 = f_2;
        SET i = i + 1;
    END WHILE;
    SET out_fib = f_0;
RETURN out_fib;
END $$