**創建**
```
delimiter $$;
create procedure test1(in age int)
begin
if age >= 18 && age < 60 then
select "成年人";
elseif age>60 then
select "老年人";
else
select "未成年人";
end if;
end
$$;
delimiter ;
```
**ifnull**
```
select ifnull('空時候顯示第二個參數','默認參數');
```
