Question

很长一段时间我使用这种方法来命令我的列表（用于html选择）：

SELECT '' AS ID, '' AS Name UNION 
SELECT ID, Name FROM (SELECT ID, Name FROM myTable ORDER BY Name) AS myTableTmp

但在更新到我发现的新MySQL（MariaDB）版本后，此排序不再有效。就像这里解释的那样，它与SQL标准冲突：https://www.somesite.com

获得所需订单的最佳做法是什么？或者我应该使用简单的方法，并将LIMIT 65000添加到嵌套查询？

修改

嗯，我原来的例子不够精确，所以人们能够误解我。这是更正的例子：

CREATE TABLE IF NOT EXISTS `myTable` (
  `ID` int(11) NOT NULL AUTO_INCREMENT,
  `Name` varchar(120) DEFAULT NULL,
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=4 ;


INSERT INTO `myTable` (`ID`, `Name`) VALUES
(1, 'Banana'),
(2, 'Apple'),
(3, NULL);

如果我选择旧版本：

SELECT '0' AS ID, '-' AS Name UNION 
SELECT ID, Name FROM (SELECT ID, Name FROM myTable ORDER BY Name) AS myTableTmp

我明白了：

0   -
3   NULL
2   Apple
1   Banana

我如何在新的MySQL版本中获得相同的结果？

Answer 1

否则您可以通过外部移动订单：

SELECT 
    ID, Name
FROM
    (SELECT '' AS ID, '' AS Name UNION SELECT 
        ID, Name
    FROM
        yourTable) AS yourTableTmp
ORDER BY Name;

Answer 2

您可以使用ORDER BY CASE ... END更改defualt排序行为以获得预期结果。

工作原理

所有＆＃39; - ＆＃39;价值得到了位置＆＃34; 1＆＃34;在ORDER BY中所有NULL值都得到位置＆＃34; 2＆＃34;在ORDER BY中所有名字都得到位置＆＃34; 3 +＆＃34;并按字母顺序排序。

<强>查询

SELECT '0' AS ID, '-' AS Name UNION 
SELECT ID, Name FROM (
  SELECT
     ID
   , Name
  FROM
   myTable
) AS myTableTmp
ORDER BY
 CASE 
  WHEN 
   Name = '-'
  THEN
   1
  WHEN 
   Name IS NULL
  THEN
   2
  ELSE 
   Name
 END

参见演示https://www.db-fiddle.com/f/xcy45sUEDKN9gJhNpVqoHd/2

但如果有人说出姓名＆＃39; - ＆＃39;在表？我可能会错误的ID 那个案子......

<强>查询

SELECT
   '0' AS ID
 , '-' AS Name
 , 0 AS position

UNION

SELECT
   ID
 , Name
 , CASE
     WHEN 
      Name IS NULL
     THEN 
      2
     ELSE
      3
   END AS position
FROM (
   SELECT
       ID
     , Name
   FROM
    myTable 
) AS myTableTmp

ORDER BY 
   position
 , name ASC

参见演示https://www.db-fiddle.com/f/xcy45sUEDKN9gJhNpVqoHd/7

Answer 3

我想，momet上最干净的SQL解决方案就像这里一样 Using union and order by clause in mysql

SELECT ID, Name FROM (
SELECT '0' AS ID, '-' AS Name, 1 AS Rank UNION 
SELECT ID, Name, 2 AS Rank FROM myTable
) AS myTableTmp ORDER BY Rank, Name

MySQL - ORDER BY与UNION的一部分

3 个答案: