我的查询在下面（它搜索父母和孩子4个级别上下）。这样，我得到一个“num”值中找到的行数：大约~22k行。
SELECT COUNT(fts_trip_id) AS num
FROM feed_trips_se
JOIN departures ON d_departure_id=fts_trip_departure_id
JOIN destinations ON destinations.d_destination_id=d_departure_id
LEFT JOIN destinations AS destChild1 ON destChild1.d_destination_parent_id=destinations.d_destination_id
LEFT JOIN destinations AS destChild2 ON destChild2.d_destination_parent_id=destChild1.d_destination_id
LEFT JOIN destinations AS destChild3 ON destChild3.d_destination_parent_id=destChild2.d_destination_id
LEFT JOIN destinations AS destChild4 ON destChild4.d_destination_parent_id=destChild3.d_destination_id
LEFT JOIN destinations AS destParent1 ON destParent1.d_destination_id=destinations.d_destination_parent_id
LEFT JOIN destinations AS destParent2 ON destParent2.d_destination_id=destParent1.d_destination_parent_id
LEFT JOIN destinations AS destParent3 ON destParent3.d_destination_id=destParent2.d_destination_parent_id
LEFT JOIN destinations AS destParent4 ON destParent4.d_destination_id=destParent3.d_destination_parent_id
WHERE fts_trip_date>=NOW()
ORDER BY fts_trip_date ASC, fts_trip_price ASC
然而，由于我使用了大量LEFT JOIN，因此〜22k的数量不是正确的行程数量。我需要按实际的fts_trip_id对这些行进行分组。
不幸的是，当我执行GROUP BY时，我获得的行数与正确的行程数（~8k）相同，而不是获得正确行程数的单行。然后所有行都显示一个数字，通常是1，但也是10或13。
老实说，当我使用GROUP BY函数时，我不知道为什么我没有得到~8k的单行值。任何人都可以帮助我吗？