查询与其他有价值的相应元素找到元组X

Question

如果我们称之为数据如下表：
(id, n1, n2, n3, n4)
111, 2, 4, 7, 0
444, 1, 1, 2, 1
555, 1, 1, 2, 0
777, 5, 3, 8, 0

我们如何只（2,4,7）获得和（5,3,8 ）？

SELECT DISTINCT n1,n2,n3 
FROM data 
WHERE n4 = 0; 

不起作用，因为它也返回（1,1,2）元组。我只需要一直有n4 = 0的元组。

Answer 1

其中一个选项是使用EXCEPT：

SELECT n1, n2, n3 
FROM data 
WHERE n4 = 0 

EXCEPT 

SELECT n1, n2, n3 
FROM data 
WHERE n4 <> 0 

Answer 2

你可以使用JOIN自我：

SELECT d.n1, d.n2, d.n3 
FROM data d 
LEFT JOIN data d2 ON (d.n1 = d2.n1 AND d.n2 = d2.n2 AND d.n3 = d3.n3 AND d.n4 != d2.n4) 
WHERE n4 = 0 AND d2.id IS NULL 

Answer 3

SELECT 
    d.n1, d.n2, d.n3 
FROM 
    data d 
WHERE 
    d.n4 = 0 
    AND 
    NOT EXISTS (SELECT * 
     FROM 
      data d2 
     WHERE 
      d.id = d2.id 
      AND 
      --3 columns = 3 pairs. n1-n2, n1-n3, n2-n3 
      (d.n1 = d2.n2 OR d.n1 = d2.n3 OR d.n1 = d2.n3)) 

编辑：

如果1,1,2是不同的，以1,2,1然后

SELECT 
    MIN(id), n1, n2, n3 
FROM 
    data 
WHERE 
    n4 = 0 
GROUP BY 
    n1, n2, n3 
HAVING 
    COUNT(*) = 1 

Answer 4

测试平台：

create table data(id integer, n1 integer, n2 integer, n3 integer, n4 integer); 

insert into data(id, n1, n2, n3, n4) 
values (111, 2, 4, 7, 0), (444, 1, 1, 2, 1), 
     (555, 1, 1, 2, 0), (777, 5, 3, 8, 0); 

假设N4不能为空或负：

select n1, n2, n3 from data group by n1, n2, n3 having max(n4)=0; 

n1 | n2 | n3 
----+----+---- 
    2 | 4 | 7 
    5 | 3 | 8 
(2 rows) 

，如果你不能假设：

insert into data(id, n1, n2, n3, n4) 
values (881, 1, 1, 1, -1), (882, 1, 1, 1, null), (883, 1, 1, 1, 0); 

select n1, n2, n3 
from data 
group by n1, n2, n3 
having sum(case when n4=0 then 0 else 1 end)=0; 

n1 | n2 | n3 
----+----+---- 
    2 | 4 | 7 
    5 | 3 | 8 
(2 rows) 

Answer 5

似乎相当简单：

SELECT n1, 
     n2, 
     n3 
FROM data 
GROUP BY n1, 
      n2, 
      n3 
HAVING Max(n4)=0 AND MIN(n4)=0; 

这将仅基于n1，n2，n3元组进行选择，并且元组的所有n4值都为0