How to delete duplicate records in oracle keeping one record. Some duplicate values/rows are inserted in it.
How to delete duplicate records in oracle keeping one record. Aug 29, 2025 · Learn Oracle SQL techniques to identify, remove, and prevent duplicate records with practical examples, performance tips, and best practices. Some duplicate values/rows are inserted in it. Any help is highly appreciated. The following lists the duplicates, but I don't know how to delete the duplicates and just k Jul 23, 2025 · SQL query to delete duplicate rows typically involves identifying duplicates using functions like ROW_NUMBER() or COUNT() and making sure that only one copy of each record is kept in the table. If not handled properly, duplicates can lead to: Inaccurate Data Reporting: Reports may contain false information. Pls give me some suggestion TOM. Mar 20, 2022 · If it was a primary key, it would contain unique values across all rows, and there would be no duplicates. Please kind your advice . How To Delete Duplicate Records In Oracle Keeping One Record 3 You can change the number duplicate preserved by changing the final where clause to Where RN N with N 1 I was thinking N 0 would delete all rows that have duplicates but it would just delete all rows 4 Added the Sum partition field the CTE query which will tag each row with the May 24, 2011 · I have unique id and email fields. delete from test1 where rowid not in (select min (rowid) from test1 group by rc_no); even after incraesing the rollback segs tablespace to 7gb we are not getting desired results and while using Jan 29, 2016 · An explanation of how to find rows with duplicate values in a table using SQL. Feb 10, 2009 · I'm testing something in Oracle and populated a table with some sample data, but in the process I accidentally loaded duplicate records, so now I can't create a primary key using some of the columns. @BobJarvis-ReinstateMonica A record is duplicate if all the column have same values for more than one rows. How can I achieve this? Dec 6, 2023 · The most common way to remove duplicate rows from our query results is to use the DISTINCT clause. Duplicate rows can occur for various reasons, such as data entry errors or system glitches. I only want to keep one Email address of all the duplicates but with the latest id (the last inserted record). [![enter image description her Jan 29, 2004 · plz explain how to remove duplicate records from a large table containing about 5 million records in a single run and with a lesser time. Oct 20, 2020 · I want to delete duplicate rows (excess rows) and retain only one row. How To Delete Duplicate Records In Oracle Keeping One Record WEB Dec 18 2023 nbsp 0183 32 How to delete duplicate rows from Oracle Here are some of the ways to delete duplicate rows in an easy manner A Fast method but you need to recreate all oracle indexes triggers create table my table1 as select distinct from my table drop my table rename my Duplicate records can cause a variety of issues in your Oracle database, such as skewing query results or taking up unnecessary storage space. Jan 6, 2025 · Learn how to identify, merge, and remove duplicate records in large databases using SQL. Jul 9, 2015 · Delete from ap where ap. com Jun 12, 2025 · When you try to enforce a primary key on an existing table with duplicate values, Oracle will throw an error because primary keys must be unique and non-null. Feb 18, 2025 · So as shown, there are many ways to delete duplicate rows in the tables. But is there any possibility to delete the duplicate records in a table without using rowid and rownum. i would be Jul 23, 2025 · How to delete duplicate rows based on one column in SQL? To delete duplicates based on one column, use a self-join on the table and delete the rows where the EMPLOYEE_ID is greater than the matching duplicate record. This tutorial shows you step by step how to delete duplicate records in Oracle Database using DELETE statement with a subquery. See full list on wikihow. The simplest way to use this is with the DISTINCT keyword at the start of the SELECT list. In this i need to delete all rows except 1 and 4 I tried using row id but it takes 3rd row as unique as well and deletes only 2nd row . I need to delete 2 nd and 3rd row . Jun 18, 2020 · I have VK_MODIFY table where i want to delete all the duplicate data by combination of ORDERID and EXTORID and keep only the one which has latest SYSTEM_INSERTED_AT. But, I need to keep one copy. name); This will remove duplicates, triplicate so on. Jul 11, 2025 · In SQL, removing duplicate records is a common task, but the DISTINCT keyword can sometimes lead to performance issues, especially with large datasets. Explore techniques with ROW_NUMBER (), COUNT (), and DISTINCT. I'd like to only keep one row for each. This post has been answered by mathguy on Oct 20 2020. I have a table that has a lot of duplicates in the Name column. Finishes by showing how to stop people entering new duplicates! Oct 20, 2019 · How do you delete duplicate records in SQL and keep one record in Oracle? Once you’ve found the duplicate records in a table, you often want to delete the unwanted copies to keep your data clean. rowid not in ( select min (rowid) from ap a group by a. my friend who is working in Oracle for arnd 4 years says that it is not possible. And delete them. Feb 14, 2022 · The first two rows are duplicates, as are the last three rows. The DISTINCT clause requires sorting and comparing records, which can increase the processing load on the query engine. Emails get duplicated. Jun 30, 2012 · I need to delete duplicate records from one table with keeping one copy of original. Aug 20, 2007 · Questions how to delete duplicate records from table Connor and Chris will both be at AI World from October 12 to October 17 , the premier Oracle conference of 2025. I need to keep only one row remaining row will be deleted. May 10, 2012 · Try with this. Jun 19, 2002 · Hi Tom, If there is any duplications of records in a table, we know how to eliminate the duplicate rows using rowid. What is the best way of writing the PL/SQL block or query to do this? Here, if I want to keep both the values of C3 ( meaning 'a' and 'b' both), what should be done? More precisely, I want to see the result like: scott@ORA8I. Regardless, below are two options for finding and deleting duplicate rows even when there’s no primary key. i tried it with following query but it takes 10 hours of time. DELETE FROM firsttable WHERE unique_ID NOT IN (SELECT MAX(unique_ID) FROM firsttable GROUP BY FID) EDIT: One explanation: SELECT MAX(unique_ID) FROM firsttable GROUP BY FID; This sql statement will pick each maximum unique_ID row from each duplicate rows group. Jun 10, 2011 · Hi, I'm having millions of records in the table . Dec 28, 2000 · I would like to delete the duplicate record on this combination and retain either value of C3. In this case the duplicate rows contain duplicate values across all columns, including the ID column. I just want to delete duplicate rows but also want to retain the last duplicate row. WORLD> select * from t1 May 8, 2013 · In case there are multiple duplicate rows to delete and all fields are identical, no different id, the table has no primary key , one option is to save the duplicate rows with distinct in a new table, delete all duplicate rows and insert the rows back. These commands could be handy in many situations and can be used depending on the requirement. I used this command- Delete from table where rowid hot in (select max (rowid) from table group by column having count (*)>1) All duplicate records are deleting successfully. Here’s how you can identify and remove duplicates and then add the primary key constraint safely. Min (rowid) or max (rowid) you have to choose either you want to store the first/oldest inserted record or latest/last inserted record. And delete statement will keep these maximum unique_ID rows and delete other rows of each duplicate group. It will keep one occurerrence for one record. But i think there should be some way to do this. . If you're in Vegas, please come say Hi or pop into our sessions Jan 26, 2023 · This Oracle tutorial will illustrate how to Delete Duplicate Rows in Oracle 21C using rownum, row_number, and rowid with examples. Jan 29, 2004 · plz explain how to remove duplicate records from a large table containing about 5 million records in a single run and with a lesser time. In this article, we will explore four different methods to identify and delete duplicate records in an Oracle database. In this article, we’ll explain various alternatives to remove duplicates in SQL, including using ROW_NUMBER (), self-joins Deleting duplicate rows in a database table is a common task in SQL, and it’s important for maintaining data integrity. t4gz dthlc9 hxigd yuq9 puqwj ykys1 osfmjsf mvf 53vp3zp mfi