Question

假设我有一个这样的表：

表1：

name     favorite_music
 a         country
 b         rock
 a         jazz
 b         jazz

如何进行此查询：找到favorite_music风格 和“jazz”的名称。对于上面的例子，它应该只是“a”。

Answer 1

这应该得到他们：

select name
from table1
where favorite_music = 'country'
intersect
select name
from table1
where favorite_music = 'jazz'

编辑：问题不是很清楚。上面的查询将返回每个名称，其中爵士乐和国家/地区都是最喜欢的音乐风格（在您的示例表格中，名称='a'）

编辑2 ：只是为了好玩，一个例子应该使用子查询进行一次扫描：

select name from (
    select 
    name, 
    count(case when favorite_music = 'country' then 1 end) as likes_country,
    count(case when favorite_music = 'jazz' then 1 end) as likes_jazz,
    from table1
    where favorite_music in ('country', 'jazz')
    group by name
) where likes_country > 0 and likes_jazz > 0

Answer 2

SELECT t1.name  
FROM table1 as t1  
INNER JOIN table1 AS t2 ON t1.name = t2.name 
WHERE t1.favorite_music = 'jazz' AND t2.favorite_music = 'country'

Answer 3

这将返回所有至少国家/地区和爵士乐最喜欢的音乐的名称：

select name from table1 where
  favorite_music in ('country', 'jazz')
group by name having count(name) = 2

这将返回所有完全（不是更多）国家/地区和爵士乐作为喜爱音乐的名称：

select name from table1 t1 where
not exists (
  select * from table1 t2 where
    t1.name = t2.name and
    t2.favorite_music not in ('country', 'jazz')
)
group by name having count(name) = 2

双重否定可能很棘手。您可以这样阅读：选择不的所有人不是国家或爵士乐的音乐。这意味着他们仅喜欢乡村或爵士音乐。 group by和having count = 2只关注他们喜欢的国家和爵士乐。

Answer 4

试试这个 - ＆gt;

select x.name from table1 x, table1 y
where
x.name = y.name and
x.favorite_music = 'country' and 
y.favorite_music = 'jazz'

Answer 5

pl / sql查询

选择名称来自table1 favorite_music ='country' 要么 favorite_music ='爵士乐' 按名称分组有COUNT（名字）＆gt; 1

OR

从中选择名称（从table1中选择名称，favorite_music favorite_music ='country' 要么 favorite_music ='爵士乐' 按名称分组，favorite_music）按名称分组有COUNT（*）＆gt; 1

一个简单的SQL查询问题

5 个答案:

pl / sql查询