我在 Oracle 中测试了一些东西，并用一些示例数据填充了一个表，但是在这个过程中我不小心加载了重复的记录，所以现在我无法使用某些列创建主键。
如何删除所有重复的行并只保留其中之一？
Juan Manuel
问问题
552284 次
24 回答
372
使用rowid伪列。
DELETE FROM your_table
WHERE rowid not in
(SELECT MIN(rowid)
FROM your_table
GROUP BY column1, column2, column3);
其中column1、column2和column3构成每条记录的识别键。您可能会列出所有列。
于 2009-02-09T17:41:15.110 回答
18
从问汤姆
delete from t
where rowid IN ( select rid
from (select rowid rid,
row_number() over (partition by
companyid, agentid, class , status, terminationdate
order by rowid) rn
from t)
where rn <> 1);
（修正了缺少的括号）
于 2011-03-18T06:11:43.427 回答
16
来自DevX.com：
DELETE FROM our_table
WHERE rowid not in
(SELECT MIN(rowid)
FROM our_table
GROUP BY column1, column2, column3...) ;
其中 column1、column2 等是您要使用的键。
于 2009-02-09T17:43:52.810 回答
13
DELETE FROM tablename a
WHERE a.ROWID > ANY (SELECT b.ROWID
FROM tablename b
WHERE a.fieldname = b.fieldname
AND a.fieldname2 = b.fieldname2)
于 2009-11-09T06:18:36.300 回答
9
解决方案1）
delete from emp
where rowid not in
(select max(rowid) from emp group by empno);
解决方案2）
delete from emp where rowid in
(
select rid from
(
select rowid rid,
row_number() over(partition by empno order by empno) rn
from emp
)
where rn > 1
);
解决方案 3)
delete from emp e1
where rowid not in
(select max(rowid) from emp e2
where e1.empno = e2.empno );
于 2015-12-31T10:32:44.897 回答
7
创建表 t2 作为 select distinct * from t1;
于 2013-01-11T17:01:33.353 回答
4
您应该使用游标循环执行一个小的 pl/sql 块并删除您不想保留的行。例如：
declare
prev_var my_table.var1%TYPE;
begin
for t in (select var1 from my_table order by var 1) LOOP
-- if previous var equal current var, delete the row, else keep on going.
end loop;
end;
于 2009-02-09T17:44:14.883 回答
3
要选择重复项，查询格式可以是：
SELECT GroupFunction(column1), GroupFunction(column2),...,
COUNT(column1), column1, column2...
FROM our_table
GROUP BY column1, column2, column3...
HAVING COUNT(column1) > 1
因此，根据其他建议，正确的查询是：
DELETE FROM tablename a
WHERE a.ROWID > ANY (SELECT b.ROWID
FROM tablename b
WHERE a.fieldname = b.fieldname
AND a.fieldname2 = b.fieldname2
AND ....so on.. to identify the duplicate rows....)
此查询将保留数据库中最旧的记录，以符合WHERE CLAUSE.
Oracle 认证助理 (2008)
于 2014-06-17T12:24:47.790 回答
3
create table abcd(id number(10),name varchar2(20))
insert into abcd values(1,'abc')
insert into abcd values(2,'pqr')
insert into abcd values(3,'xyz')
insert into abcd values(1,'abc')
insert into abcd values(2,'pqr')
insert into abcd values(3,'xyz')
select * from abcd
id Name
1 abc
2 pqr
3 xyz
1 abc
2 pqr
3 xyz
Delete Duplicate record but keep Distinct Record in table
DELETE
FROM abcd a
WHERE ROWID > (SELECT MIN(ROWID) FROM abcd b
WHERE b.id=a.id
);
run the above query 3 rows delete
select * from abcd
id Name
1 abc
2 pqr
3 xyz
于 2017-07-03T10:55:31.040 回答
2
真正大桌子的最快方式
创建具有以下结构的异常表：exceptions_table
ROW_ID ROWID OWNER VARCHAR2(30) TABLE_NAME VARCHAR2(30) CONSTRAINT VARCHAR2(30)尝试创建将被重复项违反的唯一约束或主键。您将收到一条错误消息，因为您有重复项。例外表将包含重复行的 rowid。
alter table add constraint unique --or primary key (dupfield1,dupfield2) exceptions into exceptions_table;通过 rowid 使用 exceptions_table 加入您的表并删除 dups
delete original_dups where rowid in (select ROW_ID from exceptions_table);如果要删除的行数很大，则通过rowid创建一个新表（包含所有授权和索引）反连接异常表并将原表重命名为original_dups表并将new_table_with_no_dups重命名为原始表
create table new_table_with_no_dups AS ( select field1, field2 ........ from original_dups t1 where not exists ( select null from exceptions_table T2 where t1.rowid = t2.row_id ) )
于 2014-05-30T01:07:46.577 回答
2
使用 rowid-
delete from emp
where rowid not in
(select max(rowid) from emp group by empno);
使用自连接-
delete from emp e1
where rowid not in
(select max(rowid) from emp e2
where e1.empno = e2.empno );
于 2015-12-28T14:12:14.433 回答
2
解决方案4）
delete from emp where rowid in
(
select rid from
(
select rowid rid,
dense_rank() over(partition by empno order by rowid
) rn
from emp
)
where rn > 1
);
于 2015-12-31T12:28:26.067 回答
2
1.解决方案
delete from emp
where rowid not in
(select max(rowid) from emp group by empno);
2. 斯洛伐克
delete from emp where rowid in
(
select rid from
(
select rowid rid,
row_number() over(partition by empno order by empno) rn
from emp
)
where rn > 1
);
3.解决方案
delete from emp e1
where rowid not in
(select max(rowid) from emp e2
where e1.empno = e2.empno );
4.解决方案
delete from emp where rowid in
(
select rid from
(
select rowid rid,
dense_rank() over(partition by empno order by rowid
) rn
from emp
)
where rn > 1
);
于 2016-02-10T09:29:06.543 回答
2
5.解决方案
delete from emp where rowid in
(
select rid from
(
select rowid rid,rank() over (partition by emp_id order by rowid)rn from emp
)
where rn > 1
);
于 2016-02-10T10:03:19.130 回答
2
DELETE from table_name where rowid not in (select min(rowid) FROM table_name group by column_name);
你也可以用另一种方式删除重复的记录
DELETE from table_name a where rowid > (select min(rowid) FROM table_name b where a.column=b.column);
于 2017-01-07T06:34:04.297 回答
2
这篇博文对一般情况非常有帮助：
如果行完全重复（所有列中的所有值都可以有副本），则没有可使用的列！但是要保留一个，您仍然需要为每组中的每一行设置一个唯一标识符。幸运的是，Oracle 已经有了一些您可以使用的东西。行号。Oracle 中的所有行都有一个 rowid。这是一个物理定位器。也就是说，它说明了 Oracle 在磁盘上存储该行的位置。这对每一行都是唯一的。因此，您可以使用此值来识别和删除副本。为此，在不相关的删除中将 min() 替换为 min(rowid)：
delete films
where rowid not in (
select min(rowid)
from films
group by title, uk_release_date
)
于 2021-06-07T13:28:29.270 回答
1
DELETE FROM tableName WHERE ROWID NOT IN (SELECT MIN (ROWID) FROM table GROUP BY columnname);
于 2014-01-12T05:32:10.793 回答
1
delete from dept
where rowid in (
select rowid
from dept
minus
select max(rowid)
from dept
group by DEPTNO, DNAME, LOC
);
于 2014-05-20T08:49:18.430 回答
1
为了获得最佳性能，这是我写的：（
请参阅执行计划）
DELETE FROM your_table
WHERE rowid IN
(select t1.rowid from your_table t1
LEFT OUTER JOIN (
SELECT MIN(rowid) as rowid, column1,column2, column3
FROM your_table
GROUP BY column1, column2, column3
) co1 ON (t1.rowid = co1.rowid)
WHERE co1.rowid IS NULL
);
于 2015-03-11T10:04:24.387 回答
1
检查以下脚本 -
1.
Create table test(id int,sal int);
2.
insert into test values(1,100);
insert into test values(1,100);
insert into test values(2,200);
insert into test values(2,200);
insert into test values(3,300);
insert into test values(3,300);
commit;
3.
select * from test;
您将在这里看到 6 条记录。
4.运行以下查询 -
delete from
test
where rowid in
(select rowid from
(select
rowid,
row_number()
over
(partition by id order by sal) dup
from test)
where dup > 1)
select * from test;
您将看到重复记录已被删除。
希望这能解决您的疑问。谢谢 ：）
于 2017-09-14T09:13:19.447 回答
1
我没有看到任何使用公用表表达式和窗口函数的答案。这是我发现最容易使用的。
DELETE FROM
YourTable
WHERE
ROWID IN
(WITH Duplicates
AS (SELECT
ROWID RID,
ROW_NUMBER()
OVER(
PARTITION BY First_Name, Last_Name, Birth_Date)
AS RN
SUM(1)
OVER(
PARTITION BY First_Name, Last_Name, Birth_Date
ORDER BY ROWID ROWS BETWEEN UNBOUNDED PRECEDING
AND UNBOUNDED FOLLOWING)
AS CNT
FROM
YourTable
WHERE
Load_Date IS NULL)
SELECT
RID
FROM
duplicates
WHERE
RN > 1);
需要注意的事项：
1）我们只检查分区子句中的字段是否重复。
2）如果您有某种理由选择一个副本而不是其他副本，您可以使用 order by 子句使该行具有 row_number() = 1
3）您可以通过将最后的 where 子句更改为 N >= 1 的“Where RN > N”来更改保留的数字重复（我在想 N = 0 会删除所有有重复的行，但它只会删除所有行） .
4) 在 CTE 查询中添加 Sum 分区字段，该查询将用组中的行数标记每一行。因此，要选择包含重复项的行，包括第一项，请使用“WHERE cnt > 1”。
于 2017-11-01T23:35:06.773 回答
1
解决方案 ：
delete from emp where rowid in
(
select rid from
(
select rowid rid,
row_number() over(partition by empno order by empno) rn
from emp
)
where rn > 1
);
于 2019-06-28T11:58:52.913 回答
0
create or replace procedure delete_duplicate_enq as
cursor c1 is
select *
from enquiry;
begin
for z in c1 loop
delete enquiry
where enquiry.enquiryno = z.enquiryno
and rowid > any
(select rowid
from enquiry
where enquiry.enquiryno = z.enquiryno);
end loop;
end delete_duplicate_enq;
于 2013-11-26T09:04:20.413 回答
0
这类似于最佳答案，但给了我一个更好的解释计划：
delete from your_table
where rowid in (
select max(rowid)
from your_table
group by column1, column2, column3
having count(*) > 1
);
于 2021-11-24T03:54:29.927 回答