多次leftjoin以及聚合查询导致数据不准的问题

原sql:
SELECT mmr_ID, mmr_projectName, SUM(mmr_hoursWorked.mmr_hoursWorked_hours) AS sumHours
FROM mmr 
LEFT JOIN mmr_hoursWorked
ON mmr.mmr_ID = mmr_hoursWorked.mmr_hoursWorked_project AND mmr_hoursWorked.mmr_hoursWorked_mm = "P90826"
LEFT JOIN mmr_notes
ON mmr.mmr_ID = mmr_notes.mmr_notes_MMR_ref AND mmr_notes.mmr_notes_author = "P90826"
WHERE mmr_mmAssigned = "P90826" AND mmr_projectStatus != 1 OR mmr_notes.mmr_notes_author = "P90826" AND mmr_projectStatus != 1 
GROUP BY mmr_ID


由于JOIN语句返回了结果组合，因此应该分别处理聚合和连接

新sql:
SELECT t.*
FROM
(
    SELECT mmr_ID, mmr_projectName, SUM(mmr_hoursWorked.mmr_hoursWorked_hours) AS sumHours
    FROM mmr 
    LEFT JOIN mmr_hoursWorked
    ON mmr.mmr_ID = mmr_hoursWorked.mmr_hoursWorked_project AND mmr_hoursWorked.mmr_hoursWorked_mm = 'P90826'
    WHERE mmr_projectStatus != 1 AND mmr_mmAssigned = 'P90826'
    GROUP BY mmr_ID, mmr_projectName, mmr_mmAssigned
) t
LEFT JOIN mmr_notes
ON t.mmr_ID = mmr_notes.mmr_notes_MMR_ref 
WHERE mmr_notes.mmr_notes_author = 'P90826';