根據單個列返回唯一行

Question

我有一張表（Employee）。

員工

ID Name Salary Department 
------------------------------ 
1 Steve 10000 SQ 
2 Buck 15000 AS 
3 Dan 10000 SQ 
4 Dave 10000 AS 
5 Jack 30000 AS 
6 Amy 8000 GM 

我需要爲每個部門的每一個回報員工。例如，對於上述日期我需要返回的數據如下：

ID Name Salary Department 
------------------------------ 
1 Steve 10000 SQ (I can either return Steve or Dan for this group SQ) 
2 Buck 15000 AS (I can either return Buck or Dave or Jack for this group AS) 
6 Amy 8000 GM 

Answer 1

這是一個很好用的row_number()：

select id, name, salary, department 
from (select t.*, 
      row_number() over (partition by department order by department) as seqnum 
     from t 
    ) t 
where seqnum = 1 

如果你想第一個或最後一個ID，使用order by id asc或order by id desc在row_number()分區子句中。如果你想要一個隨機的行，使用order by dbms_random.value。