mysql - 此 sql 脚本在不同的 MySQL 服务器版本上返回不同的结果？

Question

我已经在5.5.35和5.6.19上试过了。两者都返回不同的结果。 我基本上是想找到一家公司达到某个总分值(在本例中为 250)以上的确切日期

如果我的最终 sql 查询没有错误，5.5.35 似乎返回了预期的结果。

DROP TABLE IF EXISTS company_sales;

CREATE TABLE `company_sales` (
  `id_company_sales` bigint(20) NOT NULL AUTO_INCREMENT,
  `company_id` int(11) NOT NULL,
  `order_id` int(11) DEFAULT NULL,
  `date` date NOT NULL,
  `points` decimal(10,2) unsigned NOT NULL,
  `cancelled` tinyint(1) DEFAULT '0',
  `cnd1` int(11) DEFAULT NULL,
  `cnd2` varchar(128) DEFAULT '',
  `cnd3` mediumint(8) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id_company_sales`),
  UNIQUE KEY `cnd1_UNIQUE` (`cnd1`),
  KEY `index3` (`company_id`,`date`),
  KEY `order_id` (`order_id`)
) ENGINE=InnoDB AUTO_INCREMENT=56919 DEFAULT CHARSET=latin1;



INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (48712,6978,64390,'0000-00-00',76.96,1,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (49093,6978,0,'2014-11-01',256.03,0,NULL,'starting',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (47286,6978,63122,'2014-11-23',84.44,1,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (48956,6978,64811,'2014-11-28',76.96,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (48962,6978,64817,'2014-11-28',84.44,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (49042,6978,64900,'2014-11-28',57.52,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (49048,6978,64905,'2014-11-28',28.76,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (49090,6978,64945,'2014-11-28',8.35,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (53416,6978,0,'2014-12-01',106.80,0,NULL,'starting',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (53415,6978,69189,'2014-12-09',26.10,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (53459,6978,69231,'2014-12-09',16.55,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (53959,6978,69701,'2014-12-10',64.15,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (57880,4605,73805,'2014-12-18',92.13,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (57879,6212,73804,'2014-12-18',21.12,0,NULL,'',0);
INSERT INTO `company_sales` (`id_company_sales`,`company_id`,`order_id`,`date`,`points`,`cancelled`,`cnd1`,`cnd2`,`cnd3`) VALUES (57878,7395,73626,'0000-00-00',39.97,1,NULL,'',0);


SELECT 
    NULL AS id_company_sales,
    NULL AS date,
    NULL AS points,
    NULL AS total
FROM DUAL WHERE
    (@total:=0) 
UNION SELECT 
    id_company_sales,
    (date),
    points,
    @total:=@total + points AS total
FROM
    company_sales cs
WHERE
        cs.company_id = 6978
        AND cs.date >= '2014-11-21'
        AND cs.date <= '2014-12-21'
        AND cs.cancelled = 0
        AND cs.order_id != 0
        AND @total < 250
ORDER BY id_company_sales DESC
LIMIT 1;

编辑:我已经提交了一份关于 MySQL 的错误报告 http://bugs.mysql.com/bug.php?id=75266

Answer 1

像这样使用用户定义的变量(例如 @total)有点不确定。如果您在相同的 MySQL 版本上运行相同的查询，它可能会起作用。但是，在 MySQL 版本更新时，查询优化器可能已更改并在内部以不同方式执行相同的查询。

MySQL manual还指出:

As a general rule, other than in SET statements, you should never assign a value to a user variable and read the value within the same statement. For example, to increment a variable, this is okay:

SET @a = @a + 1;

For other statements, such as SELECT, you might get the results you expect, but this is not guaranteed. In the following statement, you might think that MySQL will evaluate @a first and then do an assignment second:

SELECT @a, @a:=@a+1, ...;

However, the order of evaluation for expressions involving user variables is undefined.

总结:同一个查询的结果在不同的MySQL版本之间可能会发生变化，也可能不会发生变化。不能保证查询在任何给定的 MySQL 版本中都能按预期工作。