SQL创建函数,输入参数n, 计算1!+2!+ 3!+ …+ n! 的值

可以使用以下代码创建一个SQL函数来计算1!+2!+3!+...+n!的值：

CREATE FUNCTION factorial_sum(n INT)
RETURNS INT
BEGIN
    DECLARE i INT;
    DECLARE factorial INT;
    DECLARE sum INT;
    
    SET i = 1;
    SET sum = 0;
    
    WHILE i <= n DO
        SET factorial = 1;
        
        -- 计算i的阶乘
        DECLARE j INT;
        SET j = 1;
        WHILE j <= i DO
            SET factorial = factorial * j;
            SET j = j + 1;
        END WHILE;
        
        SET sum = sum + factorial;
        SET i = i + 1;
    END WHILE;
    
    RETURN sum;
END;

然后可以使用以下代码来调用该函数：

SELECT factorial_sum(5);

这将返回1!+2!+3!+4!+5!=153的值。