如何在Oracle中的表中查找重复值?

按计数聚合列,然后使用HAVING子句查找大于一次的值。

SELECT column_name, COUNT(column_name)
FROM table_name
GROUP BY column_name
HAVING COUNT(column_name) > 1;

另一种方式:

SELECT *
FROM TABLE A
WHERE EXISTS (
  SELECT 1 FROM TABLE
  WHERE COLUMN_NAME = A.COLUMN_NAME
  AND ROWID < A.ROWID
)

column_name . 这是删除或更新重复行的更好方法。

我能想到的最简单的方法是:

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

如果不需要知道副本的实际数量,则甚至不需要在返回的列中包含计数。例如

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

怎么样:

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

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

如果多列标识唯一行(例如关系表),则可以使用以下命令

使用行id e、 g.环境管理部(环境管理署、环境管理署、开始日期、结束日期)

select oed.empid, count(oed.empid) 
from emp_dept oed 
where exists ( select * 
               from  emp_dept ied 
                where oed.rowid <> ied.rowid and 
                       ied.empid = oed.empid and 
                      ied.deptid = oed.deptid )  
        group by oed.empid having count(oed.empid) > 1 order by count(oed.empid);

如果这样的表有主键,那么使用主键而不是rowid,例如id是pk,那么

select oed.empid, count(oed.empid) 
from emp_dept oed 
where exists ( select * 
               from  emp_dept ied 
                where oed.id <> ied.id and 
                       ied.empid = oed.empid and 
                      ied.deptid = oed.deptid )  
        group by oed.empid having count(oed.empid) > 1 order by count(oed.empid);

做

select count(j1.job_number), j1.job_number, j1.id, j2.id
from   jobs j1 join jobs j2 on (j1.job_numer = j2.job_number)
where  j1.id != j2.id
group by j1.job_number

SELECT   SocialSecurity_Number, Count(*) no_of_rows
FROM     SocialSecurity 
GROUP BY SocialSecurity_Number
HAVING   Count(*) > 1
Order by Count(*) desc 

我通常使用 Oracle Analytic 作用 ROW_NUMBER() .

c1 , c2 c3 ). 那你就走这条路,带着 ROWID 行的数目,其中 ROW_NUMBER() 是 >1 :

Select * From Table_With_Duplicates
      Where Rowid In
                    (Select Rowid
                       From (Select Rowid,
                                    ROW_NUMBER() Over (
                                            Partition By c1 || c2 || c3
                                            Order By c1 || c2 || c3
                                        ) nbLines
                               From Table_With_Duplicates) t2
                      Where nbLines > 1)

如果在检查是否重复使用时需要打印表的其他列,请执行以下操作:

select * from table where column_name in
(select ing.column_name from table ing group by ing.column_name having count(*) > 1)
order by column_name desc;

如果需要,还可以在where子句中添加一些附加过滤器。

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

1.解决方案

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

SELECT count(poid) 
FROM poitem 
WHERE poid = 50 
AND rownum < any (SELECT count(*)  FROM poitem WHERE poid = 50) 
GROUP BY poid 
MINUS
SELECT count(poid) 
FROM poitem 
WHERE poid in (50)
GROUP BY poid 
HAVING count(poid) > 1;