Question

我的问题我有一个表apidata，它为每个域保存多行数据。因此，当我查询apidata时，我自然会得到多行。有没有办法将这些行转换为列？我问，因为我已经使用查询来提取域数据（页面标题，URL，顶级域名，IP地址等），我需要添加api数据。我相信我必须在两个查询中执行此操作，但我希望每个域至少有一行来进行查询并尽可能快地循环。

所以问题是，我可以动态创建行吗？

下一个SQL小提琴=＆gt; http://sqlfiddle.com/#!2/8e408/4

（注意，我并没有将整个数据库放在影响查询的表格中。如果你认为缺少了你需要的东西，请告诉我。）

Tool_Runs （id_sha是工具运行的主要查找值）

| ID | ID_SHA                                   |
+----+------------------------------------------+
| 1  | 68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A |

域（Run_id是FK到tool_runs.id）

| ID | RUN_ID |
+----+--------+
| 1  |   1    |

API数据

| ID | DOMAIN_ID | EXPORT_COLUMN    | COLUMN_TITLE      | VALUE |
+----+-----------+------------------+-------------------+-------+
| 1  | 1         | referringDomains | Referring Domains | 10    |
+----+-----------+------------------+-------------------+-------+
| 2  | 1         | linkCount        | Backlink Count    | 55    |

现在是我的查询：

SELECT a.domain_id, a.export_column, a.column_title, a.value 
FROM apidata AS a WHERE domain_id IN
(
  SELECT d.id FROM tool_runs AS t
  JOIN domains AS d ON d.run_id = t.id
  WHERE id_sha = '68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A'
)
ORDER BY a.domain_id

我得到的是：

| DOMAIN_ID | EXPORT_COLUMN    | COLUMN_TITLE      | VALUE    |
+-----------+------------------+-------------------+----------+
| 1         | referringDomains | Referring Domains | 10       |
+-----------+------------------+-------------------+----------+
| 1         | linkCount        | Backlink Count    | 55       |

但我想要的是

| DOMAIN_ID | referringDomains | referringDomains_TITLE | linkCount | linkCount_TITLE |
+-----------+------------------+------------------------+-----------+-----------------+
| 1         | 10               | Referring Domains      | 55        | Backlink Count  |

Answer 1

您尝试将数据表行转换为列。不幸的是，MySQL没有本地数据透视表操作符，但您可以使用CASE表达式来执行此操作：

SELECT 
  a.Domain_id,
  MAX(CASE WHEN a.export_column = 'referringDomains' THEN a.value END) AS referringDomains,
  MAX(CASE WHEN a.export_column = 'referringDomains' THEN a.column_title END) AS referringDomains_TITLE,
  MAX(CASE WHEN a.export_column = 'linkCount' THEN a.value END) AS linkCount,
  MAX(CASE WHEN a.export_column = 'linkCount' THEN a.column_title END) AS linkCount_TITLE
FROM apidata AS a 
WHERE domain_id IN
(
  SELECT d.id FROM tool_runs AS t
  JOIN domains AS d ON d.run_id = t.id
  WHERE id_sha = '68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A'
) 
GROUP BY a.domain_id;

Updated SQL Fiddle Demo

请注意：如果要对export_column中的所有值执行此操作，则必须为每个值编写CASE表达式。但你可以使用动态sql这样做：

SET @ecvalues = NULL;
SET @ectitles = NULL;
SET @sql = NULL;

SELECT
  GROUP_CONCAT(DISTINCT CONCAT('MAX(IF(a.export_column = ''',
      a.export_column, ''', a.value , NULL)) AS ', '''', a.export_column , '''')
  ) INTO @ecvalues
FROM apidata a;


SELECT
  GROUP_CONCAT(DISTINCT CONCAT('MAX(IF(a.export_column = ''',
      a.export_column, ''', column_title , NULL)) AS ', '''', CONCAT(a.export_column , '_Titles'), '''')
  ) INTO @ectitles
FROM apidata a;


SET @sql = CONCAT('SELECT 
  a.Domain_id, ', @ectitles , ',', @ecvalues, '
    FROM apidata AS a 
WHERE domain_id IN
(
  SELECT d.id FROM tool_runs AS t
  JOIN domains AS d ON d.run_id = t.id
  WHERE id_sha = ''68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A''
) 
GROUP BY a.domain_id;');

prepare stmt 
FROM @sql;

execute stmt;

您可以将该查询放在存储过程中。

Updated SQL Fiddle Demo

Answer 2

作为@MahmoudGamal答案的补充，您应该知道，对于任何新的注册表（EXPORT_COLUMN），您都必须添加新的case语句。

因此，为了实现动态，您可以在dba.stackexchange上创建一个过程，如本文所述。

How to transpose/convert rows as columns in mysql

它显示了如何动态地完成它。

Answer 3

如果您想要列，请按照上面的示例继续进行转动。如果您只想要一个字符串，出于某些报告原因，请继续：

SELECT group_concat(CONCAT_WS(' ',a.domain_id, a.value, a.column_title, a.export_column, 'next row string separator'))
FROM apidata AS a WHERE domain_id IN
(
  SELECT d.id FROM tool_runs AS t
  JOIN domains AS d ON d.run_id = t.id
  WHERE id_sha = '68300DF58B2A8A6E098CB0B3D1A9AE80BBE5897A'
)
ORDER BY a.domain_id

MySQL动态地创建行

3 个答案: