MySQL--带有inout的存储过程

#带有inout模式参数的存储过程

案例一：传入a和b两个值，最终a和b的值翻倍并返回
delimiter $
create PROCEDURE myp9(inout a int,inout b int)
begin
     set a=a*2;
         set b=b*2;
end $

调用过程
先设置两个用户变量
set @m=10$
set @n=20$
然后调用
call myp9(@m,@n)$
select @m,@n$--最后查看结果

运行结果:

mysql> delimiter $
create PROCEDURE myp9(intout a int,inout b int)
begin
     set a=a*2;
         set b=b*2;
end $
1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'a int,inout b int)
begin
     set a=a*2;
         set b=b*2;
end' at line 1
mysql> delimiter $
create PROCEDURE myp9(inout a int,inout b int)
begin
     set a=a*2;
         set b=b*2;
end $
Query OK, 0 rows affected (0.00 sec)

mysql> set @a=10$
Query OK, 0 rows affected (0.00 sec)

mysql> set @b=20$
Query OK, 0 rows affected (0.00 sec)

mysql> call myp9(@a,@b)$
Query OK, 0 rows affected (0.00 sec)

mysql> select @a,@b$
+----+----+
| @a | @b |
+----+----+
| 20 | 40 |
+----+----+
1 row in set (0.06 sec)

mysql>