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
在多个列标识唯一行的情况下(例如关系表)，你可以使用以下
使用行id 例如emp_dept(empid, deptid，开始日期，结束日期) 假设empid和deptid是唯一的，并在这种情况下标识行
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);
其他回答
在多个列标识唯一行的情况下(例如关系表)，你可以使用以下
使用行id 例如emp_dept(empid, deptid，开始日期，结束日期) 假设empid和deptid是唯一的，并在这种情况下标识行
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);
我能想到的最简单的:
select job_number, count(*)
from jobs
group by job_number
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;
SELECT SocialSecurity_Number, Count(*) no_of_rows
FROM SocialSecurity
GROUP BY SocialSecurity_Number
HAVING Count(*) > 1
Order by Count(*) desc
