Select 没有排序依据的组最高记录

Question

我的来源 table 看起来像这样

cust_id  cust_name
1        John Smith
1        John K Smith
2        Mary B Snow
2        Mary Snow

我想return

cust_id  cust_name
1        John Smith
2        Mary B Snow

其中一个 cust_name 值并不优于另一个值；我只想要每个 cust_id 一行，并附有任意 cust_name。

我正在使用

select cust_id, cust_name from customers
qualify 1 = row_number() over (partition by cust_id order by cust_name desc)

但是由于 order by 子句，我不能在子查询中使用它。

有没有一种方法可以在没有（概念上不必要的）排序的情况下做到这一点？

Answer 1

select cust_id, min(cust_name) 
from customers 
group by cust_id

Answer 2

您必须在 ORDER BY 子句中使用 SELECT NULL。这样它就不会更改顺序并且 Row_Number 将按预期工作

试试这个

SELECT cust_id, cust_name FROM
(
  SELECT cust_id, cust_name ,ROW_NUMBER() OVER (PARTITION  BY cust_id ORDER BY  (SELECT NULL)) RN
  FROM customers
)Tmp WHERE RN = 1

Answer 3

如果不需要订购，只需运行这个：

SELECT cust_id, MAX(cust_name)
FROM customers
GROUP BY cust_id

Answer 4

这应该有效

select cust_id, 
min(cust_name) as cust_name
from customers 
group by cust_id

Select 没有排序依据的组最高记录

Select top record by group without order by

sql

teradata