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
SELECT SocialSecurity_Number, Count(*) no_of_rows
FROM SocialSecurity
GROUP BY SocialSecurity_Number
HAVING Count(*) > 1
Order by Count(*) desc
其他回答
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;
我通常使用Oracle分析函数ROW_NUMBER()。
假设您想检查构建在列(c1, c2, c3)上的唯一索引或主键的副本。 然后你将这样做，打开ROW_NUMBER()带来的行数为>1的行数的ROWID s:
Select *
From Table_With_Duplicates
Where Rowid In (Select Rowid
From (Select ROW_NUMBER() Over (
Partition By c1, c2, c3
Order By c1, c2, c3
) nbLines
From Table_With_Duplicates) t2
Where nbLines > 1)
按COUNT聚合列，然后使用HAVING子句查找出现多次的值。
SELECT column_name, COUNT(column_name)
FROM table_name
GROUP BY column_name
HAVING COUNT(column_name) > 1;
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
