问题描述

我有一个不需要返回任何值的存储过程.它运行顺利，没有任何问题.但是，它在完成运行后输出错误消息:

I have a stored procedure which does not need to return any values. It runs smoothly and without any problem. However, it outputs an error message after finishing its run:

错误:无数据 - 提取、选择或处理零行

Error: No data - zero rows fetched, selected, or processed

我怎样才能摆脱这个错误信息?

How can I get rid of this error message?

CREATE PROCEDURE `testing_proc`()  
    READS SQL DATA  
BEGIN  
    DECLARE done INT DEFAULT 0;
    DECLARE l_name VARCHAR(20);
    DECLARE my_cur CURSOR FOR
        SELECT name FROM customer_tbl;
    OPEN my_cur;
        my_cur_loop:
        LOOP FETCH my_cur INTO l_name;
            IF done = 1 THEN
                LEAVE my_cur_loop;
            END IF;
            INSERT INTO names_tbl VALUES(l_name);
        END LOOP my_cur_loop;
    CLOSE my_cur;
END

推荐答案

我猜你忘了在你的帖子中包含以下行:

I guess you just forgot to include the following line in your post:

DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

您的代码是正确的，但 mysql 的错误/奇怪的行为导致即使处理了警告也会出现.您可以避免这种情况，如果您将虚拟"语句添加到调用表并成功的过程的末尾，这将清除警告.(参见 http://dev.mysql.com/doc/refman/5.5/en/show-warnings.html)在你的情况下:

Your code is correct, but bug/strange behaviour of mysql causes the warning to appear even if it was handled. You can avoid that if you add a "dummy" statement to the end of your procedure that invovles a table and is successful, this will clear the warning. (See http://dev.mysql.com/doc/refman/5.5/en/show-warnings.html) In your case:

SELECT name INTO l_name FROM customer_tbl LIMIT 1;

在循环结束之后.在 MySQL 5.5.13 上，警告消失，在 Linux 和 Windows 上.我评论了 MySQL Bug 60840，我希望他们在未来的某个时间修复它......

after the end of the loop. On MySQL 5.5.13 the warning disappears, on Linux and Windows. I commented on MySQL Bug 60840 and I hope they will fix it some time in the future...

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