MySql 行到列（但动态行）

Question

这是我的 SQL table 和数据。 http://sqlfiddle.com/#!9/effe2

CREATE TABLE IF NOT EXISTS `CustomValue` (
  `id` int(11) NOT NULL,
  `customFieldId` int(11) NOT NULL,
  `relatedId` int(11) NOT NULL,
  `fieldValue` text COLLATE utf8_unicode_ci,
  `createdAt` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=MyISAM AUTO_INCREMENT=8 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

INSERT INTO `CustomValue` (`id`, `customFieldId`, `relatedId`, `fieldValue`, `createdAt`) VALUES
(1, 10, 4031, NULL, '2015-11-05 04:25:00'),
(2, 14, 4031, 'adsas@das.sadsa', '2015-11-05 04:25:00'),
(3, 13, 4031, '456', '2015-11-05 04:25:00'),
(4, 16, 4031, '2015-11-09', '2015-11-05 04:25:00'),
(5, 9, 4031, '456', '2015-11-05 04:25:00'),
(6, 11, 4031, 'dsasda', '2015-11-05 04:25:00'),
(7, 15, 4031, '1', '2015-11-05 04:25:00');

现在是这样，

id  customFieldId   relatedId   fieldValue         createdAt
1   10                 4031     (null)             November, 05 2015 04:25:00
2   14                 4031     adsas@das.sadsa    November, 05 2015 04:25:00
3   13                 4031     456                November, 05 2015 04:25:00
4   16                 4031     2015-11-09         November, 05 2015 04:25:00
5   9                  4031     456                November, 05 2015 04:25:00
6   11                 4031     dsasda             November, 05 2015 04:25:00
7   15                 4031     1                  November, 05 2015 04:25:00

我需要按 relatedId 进行分组，并为每个 relatedId 获得 1 行的最终输出。

这是引用table。

CREATE TABLE IF NOT EXISTS `CustomField` (
  `id` int(11) NOT NULL,
  `customTypeId` int(11) NOT NULL,
  `fieldName` varchar(64) COLLATE utf8_unicode_ci DEFAULT NULL,
  `relatedTable` varchar(64) COLLATE utf8_unicode_ci DEFAULT NULL,
  `defaultValue` text COLLATE utf8_unicode_ci,
  `sortOrder` int(11) NOT NULL DEFAULT '0',
  `enabled` char(1) COLLATE utf8_unicode_ci DEFAULT '1',
  `listItemTag` char(1) COLLATE utf8_unicode_ci DEFAULT NULL,
  `required` char(1) COLLATE utf8_unicode_ci DEFAULT '0',
  `onCreate` char(1) COLLATE utf8_unicode_ci DEFAULT '1',
  `onEdit` char(1) COLLATE utf8_unicode_ci DEFAULT '1',
  `onView` char(1) COLLATE utf8_unicode_ci DEFAULT '1',
  `listValues` text COLLATE utf8_unicode_ci,
  `label` varchar(64) COLLATE utf8_unicode_ci DEFAULT NULL,
  `htmlOptions` text COLLATE utf8_unicode_ci
) ENGINE=MyISAM AUTO_INCREMENT=17 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

INSERT INTO `CustomField` (`id`, `customTypeId`, `fieldName`, `relatedTable`, `defaultValue`, `sortOrder`, `enabled`, `listItemTag`, `required`, `onCreate`, `onEdit`, `onView`, `listValues`, `label`, `htmlOptions`) VALUES
(13, 1, 'HOMEEMAIL', 'people', '', 0, '1', NULL, '1', '1', '1', '1', NULL, 'Home Email', ''),
(9, 1, 'LANDPHONENO', 'people', '', 0, '1', NULL, '1', '1', '1', '1', NULL, 'Land Phone No', ''),
(10, 12, 'ABOUTME', 'people', '', 0, '1', NULL, '0', '1', '1', '1', NULL, 'About Me', ''),
(11, 3, 'PHONENUMBER2', 'people', '', 0, '1', NULL, '1', '1', '1', '1', NULL, 'Phone Number 2', ''),
(14, 3, 'ALTERNATEEMAIL', 'people', '', 0, '1', NULL, '1', '1', '1', '1', NULL, 'Alternate Email', ''),
(15, 11, 'SCHOOLING?', 'people', '', 0, '1', NULL, '1', '1', '1', '1', NULL, 'Schooling?', ''),
(16, 4, 'JOINDATE', 'people', '', 0, '1', NULL, '1', '1', '1', '1', NULL, 'Join Date', '');

最终输出应该是，

relatedId | Alternate Email | Home Email | Join Date | Land Phone No | Phone Number 2 | Schooling?
--------------------------------------------------------------------------------------------------
4031      | adsas@das.sadsa | 456        | 2015-11-09| 456           | dsasda         | 1

relatedId | Alternate Email | Home Email | Join Date | Land Phone No | Phone Number 2 | Schooling? | Interest
--------------------------------------------------------------------------------------------------
4033      | adsas@das.sadsa | 456        | 2015-11-09| 456           | dsasda         | 1 | Drawing

phpmyadmin 的输出

Answer 1

你在这里需要的是 PIVOT 行到列，MySQL 但是没有像 SQL Server 或 Oracle 这样的本地数据透视运算符。但是您可以将 CASE 表达式与 group by 一起使用，如下所示：

SELECT 
  v.relatedId, v.CreatedAt,
  MAX(IF(f.fieldName = 'ABOUTME', COALESCE(v.fieldValue, f.defaultValue) , NULL)) AS 'ABOUTME',
  MAX(IF(f.fieldName = 'ALTERNATEEMAIL', COALESCE(v.fieldValue, f.defaultValue) , NULL)) AS 'ALTERNATEEMAIL',
  MAX(IF(f.fieldName = 'HOMEEMAIL', COALESCE(v.fieldValue, f.defaultValue) , NULL)) AS 'HOMEEMAIL',
  MAX(IF(f.fieldName = 'JOINDATE', COALESCE(v.fieldValue, f.defaultValue) , NULL)) AS 'JOINDATE',
  MAX(IF(f.fieldName = 'LANDPHONENO', COALESCE(v.fieldValue, f.defaultValue) , NULL)) AS 'LANDPHONENO',
  MAX(IF(f.fieldName = 'PHONENUMBER2', COALESCE(v.fieldValue, f.defaultValue) , NULL)) AS 'PHONENUMBER2',
  MAX(IF(f.fieldName = 'SCHOOLING?', COALESCE(v.fieldValue, f.defaultValue) , NULL)) AS 'SCHOOLING?'
FROM customField AS f
INNER JOIN Customvalue AS v ON f.Id = v.customFieldId 
GROUP BY   v.relatedId, v.CreatedAt;

要动态地执行此操作，您必须像这样使用动态 sql 来执行此操作：

SET @Colvalues = NULL;
SET @sql = NULL;

SELECT
  GROUP_CONCAT(DISTINCT CONCAT('MAX(IF(f.fieldName = ''',
      f.fieldName, ''', COALESCE(v.fieldValue, f.defaultValue) , NULL)) AS ', '''', f.fieldName , '''')
  ) INTO @Colvalues
FROM customField AS f
INNER JOIN Customvalue AS v ON f.Id = v.customFieldId;


SET @sql = CONCAT('SELECT 
    v.relatedId, v.CreatedAt, ', @Colvalues , '
FROM customField AS f
INNER JOIN Customvalue AS v ON f.Id = v.customFieldId 
GROUP BY   v.relatedId, v.CreatedAt;');

PREPARE stmt 
FROM @sql;

EXECUTE stmt;

注意：

如果字段值为空，它将设置默认值字段的值，这就是 COALESCE(v.fieldValue, f.defaultValue) 所做的。
您可以通过添加 WHERE v.fieldValue IS NOT NULL.

NULL

Aboutname

这会给你：

MySql 行到列（但动态行）

MySql rows in to columns (but dynamic rows)

mysql

sql

database

pivot

entity-attribute-value