Question

Table 1

Name, Vehicle
P1, Car
P1, Motorcylce
P1, Truck
P1, Helicopter
P2, Car
P3, Motorcycle
P4, Motorcycle
P4, Car
P5, Car
P5, Truck
P6, Motorcycle
P6, Truck
P7 Truck

如何查询上表，以便只有拥有汽车或摩托车或必须同时拥有汽车和摩托车的人返回。

所以

P2 -> only has a car (valid)
P3 -> only has a motorcyle (valid)
P4 -> has both car and motorcycle (valid)

已退回

Answer 1

这是使用conditional aggregation的一种方法：

select name
from yourtable
group by name
having count(case when vehicle = 'Car' then 1
                  when vehicle = 'Motorcycle' then 1
             end) = count(*)

Sample Fiddle Demo

如果您不希望自己返回的人有多于一辆汽车或摩托车（例如，P8有2辆汽车），请使用count(distinct vehicle)来排除这些记录。不清楚是否重要。

Answer 2

您可以尝试以下查询：

select Name from table 
where Name  not in (select distinct Name from table where Vehicle in 
('Helicopter','Truck'))

Answer 3

EXCEPT归还那些非汽车或摩托车的人。

select name from tablename
except
select name from tablename where vehicle not in ('Car', 'Motorcycle')

额外的WHERE子句可以加快速度：

select name from tablename where vehicle in ('Car', 'Motorcycle')
except
select name from tablename where vehicle not in ('Car', 'Motorcycle')

Answer 4

我会这样写：

select name
from yourtable
where vehicle in ('car', 'motorbike')
group by name
having count(*) = 2;

这假定每种类型只有一行。如果没有，请使用count(distinct)：

select name
from yourtable
where vehicle in ('car', 'motorbike')
group by name
having count(distinct vehicle) = 2;

Answer 5

我会使用NOT EXISTS：

select t.*
from table t
where not exists (select 1 
                  from table t1 
                  where t1.name = t.name and 
                        t1.Vehicle in ('Helicopter', 'Truck')
                 );

返回仅拥有汽车，摩托车或汽车和摩托车的人的列表

5 个答案: