MySQL使用表联接更改数据集。。我所要求的可能吗？

这是一个复杂的问题，请耐心听我说。我使用3个不同的表来创建一个结果集。详情如下:

customer_address_entity
    entity_id | entity_type_id | attribute_set_id | increment_id | parent_id | create_at | update_at | is_active

customer_entity_int
    value_id | entity_type_id | attribute_id | entity_id | value


customer_address_entity_varchar
    value_id | entity_type_id | attribute_id | entity_id | value

好的，现在你有了结构，这是我迄今为止构建的SQL调用：

SELECT CAE.entity_id, 
       CEI.value AS default_entity_id, 
       CAEV.attribute_id, 
       CAEV.value 
FROM   customer_address_entity AS CAE 
       JOIN customer_entity_int AS CEI 
         ON CEI.entity_id = CAE.parent_id 
            AND CEI.attribute_id = '13' 
       JOIN customer_address_entity_varchar AS CAEV 
         ON CAEV.entity_id = CAE.entity_id 
WHERE  CAE.parent_id = '2328' 
       AND CAE.is_active = 1 

这将输出以下示例数据集：

 ID     default  att   value

'1567', '1567', '19', 'John'
'1567', '1567', '21', 'Doe'
'1567', '1567', '23', 'Johns Company'
'1567', '1567', '25', 'Johns City'
'1567', '1567', '26', 'Johns Country'
'1567', '1567', '27', 'Johns State'
'1567', '1567', '29', 'Johns Zip Code'
'1567', '1567', '30', 'Johns Phone'
'1567', '1567', '31', 'Johns Fax'
'1568', '1567', '19', 'Jane'
'1568', '1567', '21', 'Doe'
'1568', '1567', '23', 'Janes Company'
'1568', '1567', '25', 'Janes City'
'1568', '1567', '26', 'Janes Country'
'1568', '1567', '27', 'Janes State'
'1568', '1567', '29', 'Janes Zip'
'1568', '1567', '30', 'Janes Phone'
'1568', '1567', '31', 'Janes Fax'
'1569', '1567', '19', 'Frank'
'1569', '1567', '21', 'Frunz'
'1569', '1567', '23', 'Franks Company'
'1569', '1567', '25', 'Franks City'
'1569', '1567', '26', 'Franks Country'
'1569', '1567', '27', 'Franks State'
'1569', '1567', '29', 'Franks Zip'
'1569', '1567', '30', 'Franks Phone'
'1569', '1567', '31', 'Franks Fax'

在这段代码的最后一部分，我想根据编号

UNIQUE

实体id

（返回数据集即15671568和1569中的第1列）创建X个行编号（在本例中为3）。预期的最终结果是：

'1567', '1567', 'John', 'Doe', 'Johns Company', 'Johns City', 'Johns State', 'Johns Zip Code', 'Johns Phone', 'Johns Fax'
'1568', '1567', 'Jane', 'Doe', 'Janes Company', ...  etc
'1569', '1567', 'Frank', 'Franz', 'Franks Comapny', ...   etc        

这可能吗

编辑多亏了戈登·林诺夫——答案优雅而简单！我自己做了一些修改，但会接受戈顿的答案并投票表决。以下是我所做的编辑，效果很好

select entity_id,
   if(entity_id = default_entity_id, 'true', 'false') as default_entity,
   max(case when attr = '19' then `value` end) as `FirstName`,
   max(case when attr = '21' then `value` end) as `LastName`,
   max(case when attr = '23' then `value` end) as `CompanyName`,
   max(case when attr = '25' then `value` end) as `City`,
   max(case when attr = '27' then `value` end) as `State`,
   max(case when attr = '29' then `value` end) as `ZipCode`,
   max(case when attr = '30' then `value` end) as `PhoneNumber`,
   max(case when attr = '31' then `value` end) as `Fax`

from (SELECT CAE.entity_id, CEI.value AS default_entity_id, CAEV.attribute_id AS attr, CAEV.value 
  FROM   customer_address_entity CAE 
         JOIN customer_entity_int CEI 
           ON CEI.entity_id = CAE.parent_id 
              AND CEI.attribute_id = '13' 
         JOIN customer_address_entity_varchar CAEV 
           ON CAEV.entity_id = CAE.entity_id 
  WHERE  CAE.parent_id = '2328' 
         AND CAE.is_active = 1
 ) as t
group by entity_id

---

您可以通过

分组方式执行此操作：

select entity_id,
       MAX(default) as default,
       max(case when att = '19' then value end) as FirstName,
       max(case when att = '21' then value end) as LastName,
       max(case when att = '23' then value end) as CompanyName,
       max(case when att = '25' then value end) as City,
       max(case when att = '27' then value end) as State,
       max(case when att = '29' then value end) as ZipCode,
       max(case when att = '30' then value end) as PhoneNumber,
       max(case when att = '31' then value end) as Fax
from (SELECT CAE.entity_id, CEI.value AS default_entity_id, CAEV.attribute_id, CAEV.value 
      FROM   customer_address_entity CAE 
             JOIN customer_entity_int CEI 
               ON CEI.entity_id = CAE.parent_id 
                  AND CEI.attribute_id = '13' 
             JOIN customer_address_entity_varchar CAEV 
               ON CAEV.entity_id = CAE.entity_id 
      WHERE  CAE.parent_id = '2328' 
             AND CAE.is_active = 1
     ) t
group by entity_id

此过程称为数据透视，聚合是一种解决方案（某些数据库为此使用了
pivot
关键字）。这假定每个值在每个实体中仅显示一次。另外，如果一个值不存在，它将得到NULL值。
正如答案所指出的，这就是所谓的
透视图，但MySQL没有该功能。在MySQL中，您可以将聚合函数与
CASE
语句一起使用

如果这些值都已知，则可以对其进行硬编码：

SELECT CAE.entity_id, 
    CEI.value AS default_entity_id,
    MAX(case when CAEV.attribute_id = 19 then CAEV.value else null end) FirstName,
    MAX(case when CAEV.attribute_id = 21 then CAEV.value else null end) LastName,
    MAX(case when CAEV.attribute_id = 23 then CAEV.value else null end) Company,
    MAX(case when CAEV.attribute_id = 25 then CAEV.value else null end) City,
    MAX(case when CAEV.attribute_id = 26 then CAEV.value else null end) Country,
    MAX(case when CAEV.attribute_id = 27 then CAEV.value else null end) State,
    MAX(case when CAEV.attribute_id = 29 then CAEV.value else null end) ZipCode,
    MAX(case when CAEV.attribute_id = 30 then CAEV.value else null end) Phone,
    MAX(case when CAEV.attribute_id = 31 then CAEV.value else null end) Fax
FROM   customer_address_entity AS CAE 
JOIN customer_entity_int AS CEI 
    ON CEI.entity_id = CAE.parent_id 
    AND CEI.attribute_id = '13' 
JOIN customer_address_entity_varchar AS CAEV 
    ON CAEV.entity_id = CAE.entity_id 
WHERE  CAE.parent_id = '2328' 
    AND CAE.is_active = 1 
GROUP BY CAE.entity_id, CEI.value;

或者，您可以使用准备好的语句来实现动态sql。我假设您有一个表，将每个属性值与属性名称联系起来：

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'max(case when CAEV.attribute_id = ''',
      attribute_id,
      ''' then CAEV.value else null end) AS `',
      attribute_id, '`'
    )
  ) INTO @sql
FROM customer_address_entity_varchar;

SET @sql = CONCAT('SELECT CAE.entity_id, 
                        CEI.value AS default_entity_id, ', @sql, '
                   FROM   customer_address_entity AS CAE 
                   JOIN customer_entity_int AS CEI 
                        ON CEI.entity_id = CAE.parent_id 
                        AND CEI.attribute_id = ''13' '
                    JOIN customer_address_entity_varchar AS CAEV 
                        ON CAEV.entity_id = CAE.entity_id 
                    WHERE  CAE.parent_id = ''2328''
                        AND CAE.is_active = 1 
                    GROUP BY CAE.entity_id, CEI.value');

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

您试图做的是将行转换为列；这是可能的。你提前知道这些值吗？还是未知值的数量？非常感谢！我编辑了你的代码并附加了我的问题。如此简单，但强大！爱死它了！