MySQL查詢相結合的行

Question

我有這樣

id | fieldno | fieldvalue Id|taxper|value 
1 | 10  |   2 | 0 | 100  
1 | 20  |   2 | 5 | 110 
1 | 30  |   2 | 10| 200 
1 | 40  | 

像

id 0% 5% 10 % 
1 100 110 200 

我要行結合成不同的列

Answer 1

對於當前採樣數據所需的輸出表結構，這是簡單的數據透視案例：

select 
    id, 
    max(if(taxper=0, value, null)) as `0%`, 
    max(if(taxper=5, value, null)) as `5%`, 
    max(if(taxper=10, value, null)) as `10%` 
from table1 
group by id 

SQLFiddle DEMO HERE

如果有很多值的taxper，那麼你可能需要這樣：

SET @sql = NULL; 
SELECT 
    GROUP_CONCAT(DISTINCT 
    CONCAT(
     'MAX(IF(taxper = ''', 
     taxper, 
     ''', value, NULL)) AS `', 
     taxper, '%`' 
    ) 
) INTO @sql 
FROM Table1; 
SET @sql = CONCAT('SELECT id, ', @sql, ' FROM Table1 GROUP BY id'); 
PREPARE stmt FROM @sql; 
EXECUTE stmt; 
DEALLOCATE PREPARE stmt; 

SQLFiddle DEMO HERE