如何在Oracle中查找表中的重复值?

在Oracle数据库表中返回给定列的重复值及其出现次数的最简单SQL语句是什么?

例如:我有一个列为JOB_NUMBER的JOBS表。如何才能知道我是否有任何重复的JOB_NUMBERs，以及它们重复了多少次?

当前回答

我能想到的最简单的:

select job_number, count(*)
from jobs
group by job_number
having count(*) > 1;

其他回答

如果您不需要知道重复的实际数量，则甚至不需要在返回列中显示计数。如。

SELECT column_name
FROM table
GROUP BY column_name
HAVING COUNT(*) > 1

如何:

SELECT <column>, count(*)
FROM <table>
GROUP BY <column> HAVING COUNT(*) > 1;

要回答上面的例子，它看起来像:

SELECT job_number, count(*)
FROM jobs
GROUP BY job_number HAVING COUNT(*) > 1;

下面是一个SQL请求:

select column_name, count(1)
from table
group by column_name
having count (column_name) > 1;

我能想到的最简单的:

select job_number, count(*)
from jobs
group by job_number
having count(*) > 1;

1. 解决方案

select * from emp
    where rowid not in
    (select max(rowid) from emp group by empno);

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