查询（HAVING 子句）在 Mysql 版本 5.7 和 8.0 之间的行为不同

Question

所以最近我被要求将 Mysql 版本从 5.7 升级到 Mysql 8。升级后，我注意到一个奇怪的行为，即两个版本产生的结果完全不同。以下是结构和示例数据。

创建Table

DROP TABLE IF EXISTS `Schema`.`Table`;
CREATE TABLE  `Schema`.`Table` (
  `ExchNo` int NOT NULL,
  `StkID` int NOT NULL,
  `Date` date NOT NULL DEFAULT '1899-12-31',
  `Price` decimal(18,10) NOT NULL DEFAULT '0.0000000000',
  PRIMARY KEY (`ExchNo`,`StkID`,`Date`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3;

插入数据

INSERT INTO `Schema`.`Table` (`ExchNo`,`StkID`,`Date`,`Price`) 
VALUES ('1','1','2014-12-16 00:00:00','0.3200000000'),('1','1','2014-12-17 00:00:00','0.3200000000'),('1','1','2014-12-18 00:00:00','0.3350000000'),('1','1','2014-12-19 00:00:00','0.3400000000'),('1','1','2014-12-22 00:00:00','0.4200000000'),('1','1','2014-12-23 00:00:00','0.4100000000'),('1','1','2014-12-24 00:00:00','0.4250000000'),('1','1','2014-12-26 00:00:00','0.4000000000'),('1','1','2014-12-29 00:00:00','0.4150000000'),('1','1','2014-12-30 00:00:00','0.4150000000'),('1','1','2014-12-31 00:00:00','0.4250000000'),('1','6','2014-12-16 00:00:00','9.5500000000'),('1','6','2014-12-17 00:00:00','9.4300000000'),('1','6','2014-12-18 00:00:00','9.6200000000'),('1','6','2014-12-19 00:00:00','9.7500000000'),('1','6','2014-12-22 00:00:00','9.6300000000'),('1','6','2014-12-23 00:00:00','9.8500000000'),('1','6','2014-12-24 00:00:00','9.8900000000'),('1','6','2014-12-26 00:00:00','10.0000000000'),('1','6','2014-12-29 00:00:00','10.0800000000'),('1','6','2014-12-30 00:00:00','10.1600000000'),('1','6','2014-12-31 00:00:00','10.0000000000'),('1','8','2014-12-16 00:00:00','2.6900000000'),('1','8','2014-12-17 00:00:00','2.8100000000'),('1','8','2014-12-18 00:00:00','2.8000000000'),('1','8','2014-12-19 00:00:00','2.9700000000'),('1','8','2014-12-22 00:00:00','2.9400000000'),('1','8','2014-12-23 00:00:00','2.9400000000'),('1','8','2014-12-24 00:00:00','2.9500000000'),('1','8','2014-12-26 00:00:00','2.9700000000'),('1','8','2014-12-29 00:00:00','2.9100000000'),('1','8','2014-12-30 00:00:00','2.9900000000'),('1','8','2014-12-31 00:00:00','2.9000000000');

在 Mysql 5.7 中，使用下面的查询（使用用户变量），允许我获得每个 StkID 的最新 Price 考虑到数据是否很大（ 100 万行+)

SELECT  *,(@Count0:= if(@TempID0 = `StkID`, @Count0 +1, 1)) Counter,
            (@TempID0:=`StkID`) Tempid
    FROM  `Schema`.`Table`, 
          ( SELECT  @Count0:=0,@TempID0:=0 ) sqlvar
    WHERE  `Date` <= '2018-12-31 00:00:00'
    having  Counter<=1
    ORDER BY  `StkID`,`Date` DESC;

输出：

ExchNo	StkID	Date	Price	Counter	Tempid
1	1	2014-12-31	0.42500	1	1
1	6	2014-12-31	10.0000	1	6
1	8	2014-12-31	2.90000	1	8

在 Mysql 版本 8.0 上尝试相同的查询时。它只是 returns 整个 table 而没有考虑 Counter <= 1.

的 Having 子句

我可以将整个查询包装到子查询中并获得所需的结果，但这确实会显着影响性能。

Select  *
    From  
        ( SELECT  *,
                  (@Count0:= if(@TempID0 = `StkID`, @Count0 +1, 1)) Counter,
                  (@TempID0:=`StkID`) Tempid
            FROM  `Schema`.`Table`, 
                  ( SELECT  @Count0:=0,@TempID0:=0 ) sqlvar
            WHERE  `Date` <= '2018-12-31 00:00:00'
            ORDER BY  `StkID`,`Date` DESC
        ) a
    Where  Counter<=1

所以我的问题是，这是一个错误吗？如果不是，有没有一种方法可以在不影响性能的情况下有效地实现结果？还出现了一条警告消息，我不确定这是否与结果有关。

Setting user variables within expressions is deprecated and will be removed in a future release. Consider alternatives: 'SET variable=expression, ...', or 'SELECT expression(s) INTO variables(s)'.

希望有人能解答我的问题，先谢谢了！

Answer 1

我相信从 MySQL 8+ 开始，session/user 变量已被弃用。但是，你真的不再需要它们了，因为 MySQL 8+ 引入了解析函数。您可以在此处使用 ROW_NUMBER：

WITH cte AS (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY StkID ORDER BY Date DESC) rn
    FROM yourTable
    WHERE Date <= '2018-12-31'
)

SELECT *
FROM cte
WHERE rn = 1
ORDER BY stkID;

查询（HAVING 子句）在 Mysql 版本 5.7 和 8.0 之间的行为不同

Query (HAVING Clause) does not behave the same between Mysql Version 5.7 and 8.0

mysql

groupwise-maximum