MySQL 如何创建MySQL存储过程来计算阶乘？

mysql> DELIMITER //
mysql> CREATE PROCEDURE get_factorial(IN N INT)
    -> BEGIN
    ->     SET @@GLOBAL.max_sp_recursion_depth = 255;
    ->     SET @@session.max_sp_recursion_depth = 255;
    ->
    ->     CALL factorial_recursive (N, @factorial);
    ->
    ->     SELECT @factorial;
    -> END //
Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER //
mysql> CREATE PROCEDURE factorial_recursive(IN N INT,OUT factorial INT)
    -> BEGIN
    ->     IF N = 1 THEN
    ->         SET factorial := 1;
    ->     ELSE
    ->         CALL factorial_recursive (N-1, factorial);
    ->         SET factorial := N * factorial;
    ->     END IF;
    -> END //
Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER ;
mysql> Call get_factorial(10);
+--------------+
| @factorial   |
+--------------+
|       3628800 |
+--------------+
1 row in set (0.11 sec)
Query OK, 0 rows affected (0.12 sec)

mysql> Call get_factorial(5);
+-------------+
| @factorial  |
+-------------+
|         120 |
+-------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)

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