SQL顶部+计数（）混淆

Question

我下表了：
患者
ID
名
diagnosis_id

，我需要做的是让所有的患者N个最流行诊断。
而我没有得到任何使用此查询：
SELECT name FROM patients
WHERE diagnosis_id IN
(SELECT TOP(5) COUNT(diagnosis_id) FROM patients
GROUP BY diagnosis_id
ORDER BY diagnosis_id)
如何解决它？

Answer 1

SELECT name FROM patients 
WHERE diagnosis_id IN 
(
SELECT TOP(5) diagnosis_id FROM patients 
GROUP BY diagnosis_id 
ORDER BY COUNT(diagnosis_id) desc 
) 

Answer 2

select p.name from patients p 
inner join (
    select top 5 diagnosis_id, count(*) as diagnosis_count 
    from patients 
    group by diagnosis_id 
    order by diagnosis_count) t on t.diagnosis_id = p.diagnosis_id 

Answer 3

试试这个：

SELECT name FROM patients 
WHERE diagnosis_id IN 
(SELECT TOP(5) diagnosis_id FROM patients 
GROUP BY diagnosis_id 
ORDER BY COUNT(diagnosis_id)) 

Answer 4

有两件事情不对的：

首先，我会recommend using a common table expression为 “前5” 的查找，而不是一个子查询 - 到我认为它更清晰一点，虽然这里没有关系，但它在实际工作中可能会表现更好。

虽然主要问题是您要按诊断ID排序前5位查找，而不是计数。您需要改为ORDER BY COUNT(diagnosis_id)。