Output shows the 3 rows that were deleted. ![]() OVER (PARTITION BY EMPNO ORDER BY EMPNO_TSP) Now how do we use this for a delete statement? Here is the query to delete where the row number > 1 and also to use the OLD TABLE so we seeįROM (SELECT EMPNO, EMPNO_TSP, ROW_NUMBER () In Oracle, you can do this using rowid and a subquery: delete from producttable where rowid not in (select min (rowid) from producttable group by pid, pname, pprice ) Share. OVER (PARTITION BY EMPNO ORDER BY EMPNO_TSP) AS ROW_NBR Using the Row_Number ranking function along with ‘Partition By’ we can zero in on the ones that need to be deleted. Then insert the values of temporary table into the main table. Secondly delete all the rows from the main table on which we had duplicates. If this query ran, it would delete a row for every EMPNO in the table (5 rows). Firstly create a temporary table from the main table where value of rownumber1. If there was only one duplicate, and EVERY row had a duplicate, then the following could take place to find for each EMPNO the maximum You can use Common Table Expression combined with ROWNUMBER () like this (This is the best way to delete duplicates): WITH CTE AS ( SELECT t.name,t.salary ROWNUMBER () OVER (PARTITION BY t.name,t.salary ORDER BY (SELECT 1)) as rn FROM YourTable t ) DELETE FROM CTE WHERE RN > 1. What if there is more than one duplicate for some? Because of this we cannot just zero in on the max timestamp for each. PK=(EMPNO, EMPNO_TSP):Īs you can see, some rows have duplicates and some do not. Write a single SQL statement to fix the problem? That is what this article is about.ġ) Table of data with duplicates.Write a program and order the data through a cursor by primary key and execute deletes ?.In this example the timestamp column makes up part of the composite key along with the employee number. Often times we have all seen duplicate rows in table data that occurred thru some incorrect SQL or program logic. I thought it was appropriate for SQL Tricks topic. Explore them to learn about Oracle Sql even if you know Oracle Sql Oracle interview questions : Check out this page for Top 49 Oracle Interview questions and answers : Basics, Oracle SQL to help you in interviews.Additional material is also provided where clause in oracle : Restricting the data set, where clause, what is where clause in sql statement, comparison operator’s single row functions in Oracle : Check out this to find out Single row functions in sql,Oracle data functions,Numeric functions in sql ,Character function in sql oracle sql queries topic comes from a presentation at IDUG EMEA from Marcel Scheibe that was a part of many topics in his presentation. Oracle Sql tutorials : Contains the list of all the useful Oracle sql articles. Please look at below article to have deep dive in Sql So First find the duplicate using above query, then delete it and deletion count should be same as row count of query above.Now run the find duplicate query again.If no duplicate then we are good for commit We should also first find the duplicate using the query and then verify it before committing it how to find duplicate records in oracle using rowid select * from my_table where rowid not in (select max(rowid) from my_table group by column_name) So as shown,there are many ways to delete duplicate rows in the tables.These command could handy in many situation and can be used depending on the requirement.Please always make sure we have backup available before executing any statements. ![]() Row_number() over (partition by column_name order by rowid) rn (E) delete duplicate records in using oracle analytic functions delete from my_table Where exists (select 'x' from my_table t2 (D) Use exists clause delete from my_table t1 (C) Use oracle self-join to delete duplicate rows DELETE FROM my_table A WHERE ROWID > (SELECT min(rowid) FROM my_table B WHERE A.key_values = B.key_values) Select max(rowid) from my_table group by my_col_name ) The below example shows one column.if you have delete based on two column ,you can specify two columnĭelete from my_table where rowid not in ( ![]() (B) How to find and delete duplicate records in oracle using rowid. SQL> create table mytest1 as select distinct * from mytest (A) Fast method but you need to recreate all oracle indexes,triggers create table my_table1 as select distinct * from my_table Here are some of the ways to delete duplicate rows in an easy manner Please note that you must identify all the column that make the row a duplicate in the table and specify all those columns in the appropriate delete statement in SQL How to delete duplicate rows from Oracle I would be showing off few faster method to achieve it in this post. I will show the method where rowid is used and method where rowid is not used. There are many ways to oracle delete duplicate rows but keep original. We need to delete to clear off the data issues often. ![]() We often need to find and delete duplicate rows from oracle table due to many reasons in the database.
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