Navicat连接Oracle，存储过程为什么提示错误？

代码

create or replace procedure EXCHANGE(a inout number,b inout number) 
as 
temp number(10); 
begin 
temp:=a;
a:=b; 
b:=temp; 
end;

一直提示如下错误：

PLS-00103: Encountered the symbol "NUMBER" when expecting one of the following:
:=.),@%default character
The symbol ":=" was substituted for "NUMBER" to continue.

oracle的存储过程和mysql的写法不一样的，下面这么写是mysql的写法
create procedure tests(inout a int,inout b int)
begin
declare temp int;
set temp = a;
set a = b;
set b= temp;
end ;

补充一下,mysql没有number类型

oracle应该这么写的
create or replace procedure test_aa(a in out number, b in out number)
is

temp number(10);

begin
temp := a;
a := b;
b := temp

end;