SQL for a pivot table to join the custom attributes to the primary device row.

pivot table

SET @sql = NULL;
SELECT
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'MAX(IF(AttributeID = ''',
      AttributeID,
      ''', Value, NULL)) AS ',
      Label
    )
  ) INTO @sql
FROM (SELECT DeviceID, Label, v.Value, v.AttributeID FROM fac_DeviceCustomValue v, fac_DeviceCustomAttribute a WHERE v.AttributeID=a.AttributeID) s;
SET @sql = CONCAT('SELECT d.*, ', @sql, ' FROM fac_DeviceCustomValue v, fac_Device d WHERE v.DeviceID=d.DeviceID GROUP BY v.DeviceID');

PREPARE stmt FROM @sql;
EXECUTE stmt;