试图从 2 个正在连接的子查询中获取一列并且分组不起作用
Trying to grab a column from 2 subqueries being joined and grouping not working
我的桌子是什么样子的：
mysql> select * from customer limit 3;
+-------------+---------------+-----------------------+------+--------+-------------+-------+
| customer_id | customer_name | profession | age | salary | town | state |
+-------------+---------------+-----------------------+------+--------+-------------+-------+
| 1 | Julio Sperski | Architect | 70 | 52016 | Conroe | TX |
| 2 | Micah Inchley | Biological scientist | 86 | 45355 | Omaha | NE |
| 3 | Brigg Denny | Chemist | 80 | 21754 | Bakersfield | CA |
+-------------+---------------+-----------------------+------+--------+-------------+-------+
3 rows in set (0.00 sec)
mysql> select * from vehicle limit 3;
+------------+---------------+--------------------+--------+--------+---------+----------------+--------------------+-----------------------+
| vehicle_id | vehicle_plate | registration_state | color | make | model | vehicle_type | per_day_rental_fee | per_day_insurance_fee |
+------------+---------------+--------------------+--------+--------+---------+----------------+--------------------+-----------------------+
| 1 | W9FLYC7 | TX | black | toyota | cruiser | mid size sedan | 44 | 27 |
| 2 | CA1CJIZ | NE | silver | ford | se | suv | 96 | 71 |
| 3 | HB5YI9A | CA | silver | dodge | mpv | truck | 26 | 28 |
+------------+---------------+--------------------+--------+--------+---------+----------------+--------------------+-----------------------+
3 rows in set (0.00 sec)
mysql> select * from rental limit 3;
+-----------+-------------+------------+-------------------+--------------------+-------------------------+----------------------------+
| rental_id | customer_id | vehicle_id | start_rental_date | return_rental_date | per_day_rental_fee_paid | per_day_insurance_fee_paid |
+-----------+-------------+------------+-------------------+--------------------+-------------------------+----------------------------+
| 1 | 32 | 4 | 3/4/2019 | 3/6/2019 | no | no |
| 2 | 42 | 39 | 3/23/2019 | 3/24/2019 | yes | yes |
| 3 | 33 | 14 | 10/18/2020 | 10/24/2020 | no | no |
+-----------+-------------+------------+-------------------+--------------------+-------------------------+----------------------------+
3 rows in set (0.00 sec)
customer_id、vehicle_id 和 rental_id 是主键。
customer_id和vehicle_id分别是指向客户和车辆table的外键。
所以我正在尝试获取第 3 列并显示它。
查询是这样的：
对于租车公司运营的每个注册州，return 来自特定客户州的客户数量最多。就像如果有 5 个来自 TX 的客户但在 CA 租车，而只有 2 个来自 NY 的客户在 CA 注册租车，我会 return 来自 TX 的 5 个在 CA 租车，依此类推，直到我完成了所有的注册状态。
第一个查询，
我得到的最接近的是这个查询：
SELECT registration_state,
Max(count) AS count
FROM (SELECT registration_state,
Count(a.state) AS count,
a.state
FROM rental c
LEFT JOIN customer a
ON a.customer_id = c.customer_id
LEFT JOIN vehicle b
ON c.vehicle_id = b.vehicle_id
GROUP BY registration_state,
a.state)Z
GROUP BY registration_state
ORDER BY registration_state,
count DESC;
+--------------------+-------+
| registration_state | count |
+--------------------+-------+
| AL | 1 |
| CA | 5 |
| DC | 1 |
| DE | 2 |
| FL | 3 |
| IL | 2 |
| IN | 1 |
| MD | 2 |
| MI | 1 |
| MN | 1 |
| MO | 1 |
| NE | 1 |
| NV | 2 |
| NY | 3 |
| OH | 2 |
| OR | 1 |
| PA | 1 |
| SC | 1 |
| TN | 3 |
| TX | 7 |
| WA | 1 |
+--------------------+-------+
21 rows in set (0.01 sec)
但是它只显示 registration_state 和租车公司在该州租车最多但没有显示客户状态的客户状态的计数，我希望显示客户状态.
第二个查询，以下查询生成 returns 对每个注册状态的每个客户状态的租金计数：
SELECT registration_state,
Count(d.state) AS count,
d.state
FROM rental f
LEFT JOIN customer d
ON d.customer_id = f.customer_id
LEFT JOIN vehicle e
ON f.vehicle_id = e.vehicle_id
GROUP BY registration_state,
d.state
ORDER BY registration_state,
count DESC;
+--------------------+-------+-------+
| registration_state | count | state |
+--------------------+-------+-------+
| AL | 1 | NY |
| CA | 5 | CA |
| CA | 4 | MO |
| CA | 2 | IN |
| CA | 2 | TN |
| CA | 2 | TX |
| CA | 2 | OH |
| CA | 1 | FL |
| CA | 1 | AL |
| CA | 1 | MI |
| CA | 1 | NE |
| CA | 1 | WA |
| DC | 1 | CA |
| DC | 1 | IL |
| DC | 1 | TX |
| DE | 2 | NY |
| DE | 1 | FL |
| FL | 3 | NY |
| FL | 1 | AL |
| FL | 1 | OH |
| FL | 1 | CA |
| FL | 1 | FL |
| FL | 1 | MI |
| FL | 1 | TX |
| IL | 2 | OR |
| IL | 1 | TX |
| IL | 1 | CA |
| IN | 1 | NV |
| IN | 1 | CA |
| MD | 2 | WA |
| MD | 1 | OH |
| MD | 1 | MD |
| MI | 1 | PA |
| MN | 1 | PA |
| MN | 1 | TN |
| MN | 1 | FL |
| MO | 1 | NY |
| MO | 1 | SC |
| MO | 1 | OH |
| MO | 1 | OR |
| MO | 1 | CA |
| MO | 1 | FL |
| MO | 1 | TX |
| NE | 1 | CA |
| NV | 2 | FL |
| NY | 3 | TX |
| NY | 1 | CA |
| NY | 1 | FL |
| NY | 1 | MO |
| NY | 1 | NY |
| OH | 2 | OH |
| OH | 1 | TN |
| OH | 1 | NE |
| OH | 1 | PA |
| OH | 1 | DC |
| OH | 1 | NY |
| OR | 1 | IN |
| OR | 1 | CA |
| PA | 1 | MO |
| PA | 1 | DC |
| SC | 1 | FL |
| SC | 1 | NY |
| TN | 3 | TX |
| TN | 2 | CA |
| TN | 1 | FL |
| TN | 1 | PA |
| TN | 1 | MI |
| TN | 1 | OH |
| TN | 1 | OR |
| TN | 1 | MO |
| TX | 7 | NY |
| TX | 4 | TX |
| TX | 3 | FL |
| TX | 2 | MO |
| TX | 2 | MD |
| TX | 2 | DC |
| TX | 1 | IN |
| TX | 1 | OH |
| TX | 1 | CA |
| TX | 1 | NV |
| TX | 1 | OR |
| TX | 1 | IL |
| WA | 1 | TN |
| WA | 1 | MI |
+--------------------+-------+-------+
84 rows in set (0.00 sec)
正如你在上面看到的table，如果你将它与第一个table进行比较，你会发现第一个table只是return在该注册状态下租金最多的客户状态。
我试图让它看起来像这样：
+--------------------+-------+-------+
| registration_state | count | state |
+--------------------+-------+-------+
| AL | 1 | NY |
| CA | 5 | CA |
| DC | 1 | CA |
| DE | 2 | NY |
| FL | 3 | NY |
| IL | 2 | OR |
| IN | 1 | NV |
| MD | 2 | WA |
| MI | 1 | PA |
| MN | 1 | PA |
| MO | 1 | NY |
| NE | 1 | CA |
| NV | 2 | FL |
| NY | 3 | TX |
| OH | 2 | OH |
| OR | 1 | IN |
| PA | 1 | MO |
| SC | 1 | FL |
| TN | 3 | TX |
| TX | 7 | NY |
| WA | 1 | TN |
+--------------------+-------+-------+
我试过这样加入：
SELECT registration_state,
MAX(count)
FROM (
SELECT registration_state,
Count(d.state) AS count,
d.state
FROM rental f
LEFT JOIN customer d
ON d.customer_id = f.customer_id
LEFT JOIN vehicle e
ON f.vehicle_id = e.vehicle_id
GROUP BY registration_state,
d.state)W
RIGHT JOIN
(
SELECT registration_state AS registration_state2,
count(a.state) AS count2,
a.state
FROM rental c
LEFT JOIN customer a
ON a.customer_id = c.customer_id
LEFT JOIN vehicle b
ON c.vehicle_id = b.vehicle_id
GROUP BY registration_state,
a.state )z
ON z.count2=W.count
AND z.registration_state2=W.registration_state
GROUP BY registration_state
ORDER BY registration_state;
但它只是 return 与第一个查询相同，如果我将来自任一子查询的状态添加到第一行中的 select 语句，并且还在第一行按所述状态分组结束，我结束了第二个查询。
是否有关于如何以我想要的方式return的任何建议？
如果你是运行 MySQL 8.0，你可以使用window函数为每个注册状态带来租金最多的客户状态：
select registration_state, state, cnt
from (
select v.registration_state, c.state, count(*) as cnt,
rank() over(partition by v.registration_state order by count(*) desc) rn
from rental r
inner join customer c on c.customer_id = r.customer_id
inner join vehicle v on r.vehicle_id = v.vehicle_id
group by v.registration_state, c.state
) t
where rn = 1
order by registration_state;
在较早的版本中，它有点复杂。一种选择是在 having 子句中使用行限制相关子查询：
select v.registration_state, c.state, count(*) as cnt
from rental r
inner join customer c on c.customer_id = r.customer_id
inner join vehicle v on r.vehicle_id = v.vehicle_id
group by v.registration_state, c.state
having count(*) = (
select count(*)
from rental r1
inner join customer c1 on c1.customer_id = r1.customer_id
inner join vehicle v1 on r1.vehicle_id = v1.vehicle_id
where c1.state = c.state and v1.registration_state = v.registration_state
group by v1.registration_state, c1.state
order by count(*) desc limit 1
)
请注意，这两个查询都允许顶级联系（如果有的话）。
我的桌子是什么样子的：
mysql> select * from customer limit 3;
+-------------+---------------+-----------------------+------+--------+-------------+-------+
| customer_id | customer_name | profession | age | salary | town | state |
+-------------+---------------+-----------------------+------+--------+-------------+-------+
| 1 | Julio Sperski | Architect | 70 | 52016 | Conroe | TX |
| 2 | Micah Inchley | Biological scientist | 86 | 45355 | Omaha | NE |
| 3 | Brigg Denny | Chemist | 80 | 21754 | Bakersfield | CA |
+-------------+---------------+-----------------------+------+--------+-------------+-------+
3 rows in set (0.00 sec)
mysql> select * from vehicle limit 3;
+------------+---------------+--------------------+--------+--------+---------+----------------+--------------------+-----------------------+
| vehicle_id | vehicle_plate | registration_state | color | make | model | vehicle_type | per_day_rental_fee | per_day_insurance_fee |
+------------+---------------+--------------------+--------+--------+---------+----------------+--------------------+-----------------------+
| 1 | W9FLYC7 | TX | black | toyota | cruiser | mid size sedan | 44 | 27 |
| 2 | CA1CJIZ | NE | silver | ford | se | suv | 96 | 71 |
| 3 | HB5YI9A | CA | silver | dodge | mpv | truck | 26 | 28 |
+------------+---------------+--------------------+--------+--------+---------+----------------+--------------------+-----------------------+
3 rows in set (0.00 sec)
mysql> select * from rental limit 3;
+-----------+-------------+------------+-------------------+--------------------+-------------------------+----------------------------+
| rental_id | customer_id | vehicle_id | start_rental_date | return_rental_date | per_day_rental_fee_paid | per_day_insurance_fee_paid |
+-----------+-------------+------------+-------------------+--------------------+-------------------------+----------------------------+
| 1 | 32 | 4 | 3/4/2019 | 3/6/2019 | no | no |
| 2 | 42 | 39 | 3/23/2019 | 3/24/2019 | yes | yes |
| 3 | 33 | 14 | 10/18/2020 | 10/24/2020 | no | no |
+-----------+-------------+------------+-------------------+--------------------+-------------------------+----------------------------+
3 rows in set (0.00 sec)
customer_id、vehicle_id 和 rental_id 是主键。
customer_id和vehicle_id分别是指向客户和车辆table的外键。
所以我正在尝试获取第 3 列并显示它。 查询是这样的：
对于租车公司运营的每个注册州，return 来自特定客户州的客户数量最多。就像如果有 5 个来自 TX 的客户但在 CA 租车，而只有 2 个来自 NY 的客户在 CA 注册租车，我会 return 来自 TX 的 5 个在 CA 租车，依此类推，直到我完成了所有的注册状态。
第一个查询， 我得到的最接近的是这个查询：
SELECT registration_state,
Max(count) AS count
FROM (SELECT registration_state,
Count(a.state) AS count,
a.state
FROM rental c
LEFT JOIN customer a
ON a.customer_id = c.customer_id
LEFT JOIN vehicle b
ON c.vehicle_id = b.vehicle_id
GROUP BY registration_state,
a.state)Z
GROUP BY registration_state
ORDER BY registration_state,
count DESC;
+--------------------+-------+
| registration_state | count |
+--------------------+-------+
| AL | 1 |
| CA | 5 |
| DC | 1 |
| DE | 2 |
| FL | 3 |
| IL | 2 |
| IN | 1 |
| MD | 2 |
| MI | 1 |
| MN | 1 |
| MO | 1 |
| NE | 1 |
| NV | 2 |
| NY | 3 |
| OH | 2 |
| OR | 1 |
| PA | 1 |
| SC | 1 |
| TN | 3 |
| TX | 7 |
| WA | 1 |
+--------------------+-------+
21 rows in set (0.01 sec)
但是它只显示 registration_state 和租车公司在该州租车最多但没有显示客户状态的客户状态的计数，我希望显示客户状态.
第二个查询，以下查询生成 returns 对每个注册状态的每个客户状态的租金计数：
SELECT registration_state,
Count(d.state) AS count,
d.state
FROM rental f
LEFT JOIN customer d
ON d.customer_id = f.customer_id
LEFT JOIN vehicle e
ON f.vehicle_id = e.vehicle_id
GROUP BY registration_state,
d.state
ORDER BY registration_state,
count DESC;
+--------------------+-------+-------+
| registration_state | count | state |
+--------------------+-------+-------+
| AL | 1 | NY |
| CA | 5 | CA |
| CA | 4 | MO |
| CA | 2 | IN |
| CA | 2 | TN |
| CA | 2 | TX |
| CA | 2 | OH |
| CA | 1 | FL |
| CA | 1 | AL |
| CA | 1 | MI |
| CA | 1 | NE |
| CA | 1 | WA |
| DC | 1 | CA |
| DC | 1 | IL |
| DC | 1 | TX |
| DE | 2 | NY |
| DE | 1 | FL |
| FL | 3 | NY |
| FL | 1 | AL |
| FL | 1 | OH |
| FL | 1 | CA |
| FL | 1 | FL |
| FL | 1 | MI |
| FL | 1 | TX |
| IL | 2 | OR |
| IL | 1 | TX |
| IL | 1 | CA |
| IN | 1 | NV |
| IN | 1 | CA |
| MD | 2 | WA |
| MD | 1 | OH |
| MD | 1 | MD |
| MI | 1 | PA |
| MN | 1 | PA |
| MN | 1 | TN |
| MN | 1 | FL |
| MO | 1 | NY |
| MO | 1 | SC |
| MO | 1 | OH |
| MO | 1 | OR |
| MO | 1 | CA |
| MO | 1 | FL |
| MO | 1 | TX |
| NE | 1 | CA |
| NV | 2 | FL |
| NY | 3 | TX |
| NY | 1 | CA |
| NY | 1 | FL |
| NY | 1 | MO |
| NY | 1 | NY |
| OH | 2 | OH |
| OH | 1 | TN |
| OH | 1 | NE |
| OH | 1 | PA |
| OH | 1 | DC |
| OH | 1 | NY |
| OR | 1 | IN |
| OR | 1 | CA |
| PA | 1 | MO |
| PA | 1 | DC |
| SC | 1 | FL |
| SC | 1 | NY |
| TN | 3 | TX |
| TN | 2 | CA |
| TN | 1 | FL |
| TN | 1 | PA |
| TN | 1 | MI |
| TN | 1 | OH |
| TN | 1 | OR |
| TN | 1 | MO |
| TX | 7 | NY |
| TX | 4 | TX |
| TX | 3 | FL |
| TX | 2 | MO |
| TX | 2 | MD |
| TX | 2 | DC |
| TX | 1 | IN |
| TX | 1 | OH |
| TX | 1 | CA |
| TX | 1 | NV |
| TX | 1 | OR |
| TX | 1 | IL |
| WA | 1 | TN |
| WA | 1 | MI |
+--------------------+-------+-------+
84 rows in set (0.00 sec)
正如你在上面看到的table，如果你将它与第一个table进行比较，你会发现第一个table只是return在该注册状态下租金最多的客户状态。
我试图让它看起来像这样：
+--------------------+-------+-------+
| registration_state | count | state |
+--------------------+-------+-------+
| AL | 1 | NY |
| CA | 5 | CA |
| DC | 1 | CA |
| DE | 2 | NY |
| FL | 3 | NY |
| IL | 2 | OR |
| IN | 1 | NV |
| MD | 2 | WA |
| MI | 1 | PA |
| MN | 1 | PA |
| MO | 1 | NY |
| NE | 1 | CA |
| NV | 2 | FL |
| NY | 3 | TX |
| OH | 2 | OH |
| OR | 1 | IN |
| PA | 1 | MO |
| SC | 1 | FL |
| TN | 3 | TX |
| TX | 7 | NY |
| WA | 1 | TN |
+--------------------+-------+-------+
我试过这样加入：
SELECT registration_state,
MAX(count)
FROM (
SELECT registration_state,
Count(d.state) AS count,
d.state
FROM rental f
LEFT JOIN customer d
ON d.customer_id = f.customer_id
LEFT JOIN vehicle e
ON f.vehicle_id = e.vehicle_id
GROUP BY registration_state,
d.state)W
RIGHT JOIN
(
SELECT registration_state AS registration_state2,
count(a.state) AS count2,
a.state
FROM rental c
LEFT JOIN customer a
ON a.customer_id = c.customer_id
LEFT JOIN vehicle b
ON c.vehicle_id = b.vehicle_id
GROUP BY registration_state,
a.state )z
ON z.count2=W.count
AND z.registration_state2=W.registration_state
GROUP BY registration_state
ORDER BY registration_state;
但它只是 return 与第一个查询相同，如果我将来自任一子查询的状态添加到第一行中的 select 语句，并且还在第一行按所述状态分组结束，我结束了第二个查询。
是否有关于如何以我想要的方式return的任何建议？
如果你是运行 MySQL 8.0，你可以使用window函数为每个注册状态带来租金最多的客户状态：
select registration_state, state, cnt
from (
select v.registration_state, c.state, count(*) as cnt,
rank() over(partition by v.registration_state order by count(*) desc) rn
from rental r
inner join customer c on c.customer_id = r.customer_id
inner join vehicle v on r.vehicle_id = v.vehicle_id
group by v.registration_state, c.state
) t
where rn = 1
order by registration_state;
在较早的版本中，它有点复杂。一种选择是在 having 子句中使用行限制相关子查询：
select v.registration_state, c.state, count(*) as cnt
from rental r
inner join customer c on c.customer_id = r.customer_id
inner join vehicle v on r.vehicle_id = v.vehicle_id
group by v.registration_state, c.state
having count(*) = (
select count(*)
from rental r1
inner join customer c1 on c1.customer_id = r1.customer_id
inner join vehicle v1 on r1.vehicle_id = v1.vehicle_id
where c1.state = c.state and v1.registration_state = v.registration_state
group by v1.registration_state, c1.state
order by count(*) desc limit 1
)
请注意，这两个查询都允许顶级联系（如果有的话）。