存储过程实现递归算法

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以经典的阶乘算法为例。

Oracle：

sql view plain copy

1. create or replace procedure factorial(n in number, b out number)
2. is
3. c\_in number;
4. c\_out number;
5. begin
6. if n!=1 **then**
7. c\_in := n-1;
8. factorial(c\_in,c\_out);
9. b := n\*c\_out;
10. else
11. b := 1;
12. end if;
13. end;
14. /
16. --调用
17. variable r number;
18. exec factorial(6,:r);
19. print r;

MySQL：

sql view plain copy

1. drop procedure if exists factorial;
2. set @@session.max_sp_recursion_depth=99;
3. delimiter $$
5. create procedure factorial (in n bigint, out b bigint)
6. begin
7. declare c_in bigint;
8. declare c_out bigint;
9. if n!=1 **then**
10. set c_in := n-1;
11. call factorial(c\_in,c\_out);
12. set b:=n*c_out;
13. else
14. set b:=1;
15. end if;
16. end$$
18. delimiter ;
20. --调用
21. call factorial(6,@r);
22. select @r;