Oracle：仅从具有 min(id) 的行中选择值答案

【问题标题】：Oracle: select values only from row with min(id)Oracle：仅从具有 min(id) 的行中选择值
【发布时间】：2026-02-02 02:00:01
【问题描述】：

SELECT
   ass.assessmentAmount -- want to fetch assessmentAmount of min(ass.assessmentId)
   ass.assessmentId
FROM
   --bunch of joins  
WHERE
ass.assessmentId = (SELECT min(ass2.assessmentId) FROM Assessment ass2
   --same bunch of joins

看起来很混乱，因为我有 6 个条件连接，我不想重复两次。还有另一种方法吗？

【问题讨论】：

Using the MIN function in the having clause的可能重复

标签： sql oracle

【解决方案1】：

使用MIN( ass.assessmentId ) OVER ()解析函数：

SELECT *
FROM   (
  SELECT ass.assessmentAmount,
         ass.assessmentId,
         MIN( ass.assessmentId ) OVER () AS min_assessmentId
  FROM   --bunch of joins
)
WHERE assessmentId = min_assessmentId;

你也可以使用RANK():

SELECT *
FROM   (
  SELECT ass.assessmentAmount,
         ass.assessmentId,
         RANK() OVER ( ORDER BY ass.assessmentId ) AS rnk
  FROM   --bunch of joins
)
WHERE rnk = 1;

如果assessmentId 是UNIQUE 并且至少只能有一行，那么您可以将RANK 替换为ROW_NUMBER；但是，您也可以使用 ROWNUM 伪列获得所需的结果：

SELECT *
FROM   (
  SELECT ass.assessmentAmount,
         ass.assessmentId
  FROM   --bunch of joins
  ORDER BY ass.assessmentId ASC
)
WHERE ROWNUM = 1;

【讨论】：

【解决方案2】：

使用带有 row_number 的 CTE

with CTE as
(
select assessmentId, 
       assessmentAmount , 
       row_number() over (order by assessmentid asc) as rn
from --bunch of joins
)
select *
from CTE
where rn = 1

【讨论】：

如果assessmentId 列是UNIQUE，则使用ROW_NUMBER 只会给出与OP 查询相同的答案。如果多行可以具有相同的最小值assessmentId，那么这将不会给出相同的答案。