Question

我有一张地点表，一张餐馆桌子和一张赌场桌子，后两张包括他们所在地的身份。

从这些表中我想要一个新的位置表，以及一个列数，计算该位置有多少家餐馆，以及该位置有多少家赌场，除非两者都有0，在这种情况下我要排除结果中的那个位置。

以下伪代码查询对我来说只对餐厅进行上述操作有效，但我在添加赌场时遇到了麻烦。有关如何实现这一目标的任何建议吗？

SELECT r.location_id, l.name, count(r.location_id) FROM restaurants r join locations l ON r.location_id = l.id GROUP BY l.id, l.name;

这是我所拥有的表格的示例数据

Locations
 id |  name   | lat_lng  
----+---------+-----------
  1 | Florida | 3A29F3840
  2 | Nevada  | 4G32J1273
  3 | Maine   | 9Y35V9241

Restaurants
 id | location_id | name  
----+-------------+--------------------
  1 |           2 | McDonalds
  2 |           1 | Cheesecake Factory
  3 |           2 | Steak and Shake

Casinos
 id | location_id | name  
----+-------------+-----------------
  1 |           2 | Ballys
  2 |           2 | Treasure Island

我希望得到的表格的一个例子

Result
location_id | location_name | restaurant_count | casino_count  
------------+---------------+------------------+--------------
          1 | Florida       |                1 |            0
          2 | Nevada        |                2 |            2

Answer 1

左连接和分组依据，计数明显..锚定位置

SELECT l.id [Location Id], 
l.name [Location Name], 
count(distinct r.id) [Location count],
count(distinct c.id) [Casino Count] 
 FROM locations l
  left join  restaurants r  ON r.location_id = l.id
  left join casinos c on c.location_id = l.id
 GROUP BY l.id,l.name
 having count(distinct r.id)> 0 or
 count(distinct c.id) > 0

/* sample script using SQL-SERVER */


select * 
into #Locations
from (
values( 1, 'Florida', '3A29F3840'),
  (2,'Nevada','4G32J1273'),
  (3,'Maine','9Y35V9241')
 ) 
 as x (id,name,lat_lng)


select * 
into #Restaurants
from (
values( 1,2),
     (2,1),
    (3,2)
 ) 
 as x (id,location_id)

select * 
into #Casinos
from (
values( 1,2),
     (2,2)
    ) 
 as x (id,location_id)


 SELECT l.id [Location Id], 
l.name [Location Name], 
count(distinct r.id) [Location count],
 count(distinct c.id) [Casino Count] 
 FROM #locations l
  left join  #restaurants r  ON r.location_id = l.id
  left join #casinos c on c.location_id = l.id
 GROUP BY l.id,l.name
 having count(distinct r.id)> 0 or
 count(distinct c.id) > 0


 drop table #Locations
 drop table #Restaurants
 drop table #Casinos

结果

Location Id Location Name Location count Casino Count
----------- ------------- -------------- ------------
1           Florida       1              0
3           Maine         0              0
2           Nevada        2              2

计算两个表中位置的实例，在结果中存储两列

1 个答案: