Question

我有一张这样的表：

UPDATE

如何为每个传感器和fkey | sensor | depth | value -----+--------+-------+------- 1 | 1 | 1 | 34 1 | 1 | 2 | 27 1 | 2 | 1 | 22 1 | 2 | 2 | 34 1 | 2 | 3 | 56 2 | 1 | 1 | 12 2 | 1 | 2 | 24 2 | 2 | 1 | 56 3 | 1 | 1 | 43 3 | 1 | 2 | 89 3 | 1 | 3 | 97深度的GROUP_CONCAT值编写选择查询以显示此信息？

ORDER BY

Answer 1

尝试使用带有GROUP_CONCAT表达式的CASE来定位每个传感器数据。

SELECT
    fkey,
    GROUP_CONCAT(CASE WHEN sensor=1 THEN value END ORDER BY depth) AS sensor1_values,
    GROUP_CONCAT(CASE WHEN sensor=2 THEN value END ORDER BY depth) AS sensor2_values
FROM yourTable
GROUP BY fkey;

Answer 2

通过替换表名和列名

来尝试此查询

fkey是A列传感器是B列深度是C列值是D列

select A, STUFF((SELECT ', ' + D FROM tableA b 
           WHERE b.A = a.A AND b.B = 1
          FOR XML PATH('')), 1, 2, '') sensor1_values  
          , STUFF((SELECT ', ' + D FROM tableA b 
           WHERE b.A = a.A AND b.B = 2
          FOR XML PATH('')), 1, 2, '') sensor2_values
from tableA a
group by A

选择具有相同列的所有行以分隔mysql中的列

2 个答案: