MySQL中动态执行此操作的唯一方法是使用Prepared语句.这是一篇关于它们的好文章:

The only way in MySQL to do this dynamically is with Prepared statements. Here is a good article about them:

动态数据透视表(将行转换为列)

您的代码如下:

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'MAX(IF(pa.fieldname = ''',
      fieldname,
      ''', pa.fieldvalue, NULL)) AS ',
      fieldname
    )
  ) INTO @sql
FROM product_additional;

SET @sql = CONCAT('SELECT p.id
                    , p.name
                    , p.description, ', @sql, ' 
                   FROM product p
                   LEFT JOIN product_additional AS pa 
                    ON p.id = pa.id
                   GROUP BY p.id');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

请参见演示

注意:GROUP_CONCAT函数的限制为1024个字符.参见参数group_concat_max_len

NOTE: GROUP_CONCAT function has a limit of 1024 characters. See parameter group_concat_max_len