包含有特定属性的元素计数组

Question

我有一个包含3个值

CREATE TABLE x (
start  integer NOT NULL, 
end  integer NOT NULL, 
random  integer NOT NULL); 

我要计数组包含的至少一种元素与random > 42但是比大的量（GROUP BY start,end）的表一个元素。但据我所知HAVING只能用于聚合函数。

我当前的尝试：

SELECT count(*) FROM (
SELECT count(*) FROM routes 
GROUP BY start,end 
HAVING random > 42 
AND count(*) > 1); 

结果

没有这样的列：随机

什么是解决这一问题的最有效方法是什么？

Answer 1

SELECT count(*) 
FROM (SELECT SUM(case when random > 42 then 1 else 0 end) as cnt 
     FROM routes 
     GROUP BY start,end 
     HAVING count(*) > 1) as t 
WHERE cnt > 1 

Answer 2

包括像下面

SELECT count(case when random > 42 then 1 else 0 end) as computed_column 
FROM routes 
GROUP BY start, end; 

您的查询是有点怪在你的集合函数本身的条件下，它可以重新写的

SELECT COUNT(*) FROM 
(
SELECT count(*) as Count_Route 
FROM routes 
WHERE random > 42 
GROUP BY start, end 
HAVING count(*) > 1 
) XXX;