MySQL查询组合行

Question

我有这样的表结构

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

所需的输出，如

id   0%  5%   10 %
1    100 110  200

我想将行组合成不同的列

Answer 1

对于当前的样本数据，它是一个简单的支点案例：

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taxper有很多值，那么您可能需要这样：

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