在MSAccess中創建以下查詢的最有效方法是什麼？

我想這個表/查詢在MSAccess中創建以下查詢的最有效方法是什麼？

+--------+-----------------+-----------------+ 
| tag_id | attribute_name | attribute_value | 
+--------+-----------------+-----------------+ 
|  1 | tag_name  | P1001   | 
|  1 | tag_address  | N7:0   | 
|  1 | tag_description | Pump 1 Status | 
|  2 | tag_name  | P1002   | 
|  2 | tag_address  | N7:1   | 
|  2 | tag_description | Pump 2 Status | 
|  3 | tag_name  | P1003   | 
|  3 | tag_address  | N7:2   | 
|  3 | tag_description | Pump 3 Status | 
+--------+-----------------+-----------------+

轉換爲該

+----------+-------------+-----------------+ 
| tag_name | tag_address | tag_description | 
+----------+-------------+-----------------+ 
| P1001 | N7:0  | Pump 1 Status | 
| P1002 | N7:1  | Pump 2 Status | 
| P1003 | N7:2  | Pump 3 Status | 
+----------+-------------+-----------------+

我知道交叉表查詢存在，但它迫使我挑了價值聚合函數。如果我選擇First或Max它可行，但它不覺得是最有效的方法。有更好的方法嗎？

來源

2014-01-23 David

select tag_name, tag_address, tag_description from 
(
    (
     select tag_id, attribute_value as tag_name 
     from inputtable 
     where attribute_name='tag_name' 
    ) as one 
    left join 
    (
     select tag_id, attribute_value as tag_address 
     from inputtable 
     where attribute_name='tag_address' 
    ) as two 
    on one.tag_id=two.tag_id 
) 
left join 
(
    select tag_id, attribute_value as tag_description 
    from inputtable 
    where attribute_name='tag_description' 
) as three 
on one.tag_id=three.tag_id

來源

2014-01-23 13:43:42

訪問不會喜歡那個查詢。由於在第一對連接的子查詢周圍缺少括號，它會引發語法錯誤。（訪問是那樣的挑剔。） –

啊...我更像一個SQL Server的傢伙。固定。謝謝你的提示！ –

正如你在你的問題建議，

TRANSFORM MAX(attribute_value) AS thing 
SELECT tag_id 
FROM your_table 
GROUP BY tag_id 
PIVOT attribute_name IN ('tag_name','tag_address','tag_description')

會工作。另一種選擇是

SELECT tn.tag_name, ta.tag_address, td.tag_description 
FROM 
    (
     (
      SELECT 
       tag_id, 
       attribute_value AS tag_name 
      FROM your_table 
      WHERE attribute_name = 'tag_name' 
     ) AS tn 
     INNER JOIN 
     (
      SELECT 
       tag_id, 
       attribute_value AS tag_address 
      FROM your_table 
      WHERE attribute_name = 'tag_address' 
     ) AS ta 
      ON ta.tag_id = tn.tag_id 
    ) 
    INNER JOIN 
    (
     SELECT 
      tag_id, 
      attribute_value AS tag_description 
     FROM your_table 
     WHERE attribute_name = 'tag_description' 
    ) AS td 
     ON td.tag_id = tn.tag_id

但我可能只是去第一個。

來源

2014-01-23 14:23:11

在MSAccess中創建以下查詢的最有效方法是什麼？

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