Question

我正在阅读有关存储过程的文章，这是代码：

delimiter //

create procedure largest_order(out largest_id int) 
begin
  declare this_id int;
  declare this_amount float;
  declare l_amount float default 0.0;
  declare l_id int;

  declare done int default 0;
  declare continue handler for sqlstate '02000' set done = 1;
  declare c1 cursor for select orderid, amount from orders;

  open c1;
  repeat
    fetch c1 into this_id, this_amount;
    if not done then
      if this_amount > l_amount then
        set l_amount=this_amount;
        set l_id=this_id;
      end if;
    end if;
   until done end repeat; 
  close c1;

  set largest_id=l_id;

end
//

delimiter ;

我正在使用名为“mydatabase”的简单数据库。运行上面的代码后，它给了我这个错误：ERROR 1338 (42000): Cursor declaration after handler declaration 有什么问题，我该如何解决？

这是我第一次使用存储过程。

Answer 1

Per MySql docs：

游标声明必须出现在处理程序声明之前和之后变量和条件声明。

所以我更新了代码如下：

delimiter //

create procedure largest_order(out largest_id int) 
begin
  declare this_id int;
  declare this_amount float;
  declare l_amount float default 0.0;
  declare l_id int;

  -- 1. cursor finished/done variable comes first
  declare done int default 0;
  -- 2. the curser declaration and select
  declare c1 cursor for select orderid, amount from orders;
  -- 3. the continue handler is defined last
  declare continue handler for sqlstate '02000' set done = 1;


  open c1;
  repeat
    fetch c1 into this_id, this_amount;
    if not done then
      if this_amount > l_amount then
        set l_amount=this_amount;
        set l_id=this_id;
      end if;
    end if;
   until done end repeat; 
  close c1;

  set largest_id=l_id;

end
//

delimiter ;

现在工作正常。

MySql存储过程错误[ERROR 1338（42000）：处理程序声明后的游标声明]

1 个答案: