select * from mytable union select * from mytable, thsi query returns the exact records, and i guess we can use this data to build a new table or replacing the previous one. I need to get rid of the duplications, meaning that when names are shown more than once for a given month and year, I only want one of the duplicated intervention records to show up
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We extensively use GROUP BY and we all know problem with GROUP BY (We should have all selected column from select clause in group by clause, other wise we cannot use group by). The problem is: the system by mistake inserted duplicate data in R2-R5 (R1 is PK assuem autonumber) and in one of these duplicates R6 and R7 are also filled
Remove Duplicate Rows from a Table in SQL Server - CodeProject
Easiest way to delete more than one duplicate row from a table in SQL Server Introduction Most of the times, we use primary key or unique key for preventing insertion of duplicate rows in SQL Server. Is it too complicated? History 16th February, 2011: Initial post License This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL) Share email twitter facebook linkedin reddit google+ About the Author Sadeque Sharif Software Developer Meridian Group Bangladesh I am: Manager (IT) at Meridian Group
You can find an other sql tutorial titled How to delete duplicate records or rows among identical rows in a table where no primary key exists among Kodyaz SQL articles. ORDER BY ...) to Delete Duplicate Rows in SQL Table If you have duplicate rows in your MS SQL Server database tables, you may want to delete duplicate records
http://javarevisited.blogspot.com/2012/12/how-to-find-duplicate-records-in-table-mysql-query-example.htmlYou can see in first query that it listed Ruby as duplicate record even though both Ruby have different phone number because we only performed group by on name. Can you please write something about DB performance tuning as well as its being repetitvely asked to me and am unable to convince a great deal as I havent really worked on such scenarios December 17, 2012 at 8:07 AM Anonymous said..
sql - How can I remove duplicate rows? - Stack Overflow
Automatically SQL SERVER ignore (there is also an option about what to do if there will be a duplicate value: ignore, interrupt or sth) duplicate values. Factors which might favour the hash aggregate approach would be No useful index on the partitioning columns relatively fewer groups with relatively more duplicates in each group In extreme versions of this second case (if there are very few groups with many duplicates in each) one could also consider simply inserting the rows to keep into a new table then TRUNCATE-ing the original and copying them back to minimise logging compared to deleting a very high proportion of the rows
How to delete duplicate rows in sql server? - Stack Overflow
The above article will provide you the technique of how to combine all records to one good record without losing any data while removing the other duplicate records
Result set after the usage of ranking function will look as below with all ranks defined 1 for unique values and all duplicates with values greater than 1
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