MSSQL: Search for duplicates in columns based on criteria

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I am trying to create a script that will look through the sql columns and search for duplicates based on first name, last name, and date of birth. Can you advice me how I can start this? Like I can do it for one id, but I need to go through the enter list of ids and do the search

id    Forename    Surname    DateofBirth
1     John          Doe      2015-05-16
2     Martin        Rocks    2015-04-18
3     John          Doe      2015-05-16
4     Ben           Dover    2014-08-09

So in this case, I just want to write a script that can take each ID and look for duplicates based on matching Forename, Surname and Date of birth

you can use analytical function to achieve your goal like this:

select * from (
select ROW_NUMBER() OVER(PARTITION BY Forename, Surname, DateofBirth order by ID) RN,
   Forename,
   Surname,
   DateofBirth
from table_name) x
where x.rn>1

How to Find Duplicate Values in a SQL Table, Identify Duplicate Criteria. The first step is to define your criteria for a duplicate row. Do you need a combination of two columns to be unique  To find the duplicate values in a table, you follow these steps: First, define criteria for duplicates: values in a single column or multiple columns. Second, write a query to search for duplicates. If you want to also delete the duplicate rows, you can go to the deleting duplicates from a table tutorial.

use corelated subquery

select t.* from table_name t where 
exists ( select 1 from table_name t1 where t1.DateofBirth=t.DateofBirth and t1.Forename=t.Forename
          and t1.surname=t.surname 
           group by t1.DateofBirth,t1.Forename,t1.Surname
           having count(*)>1 )

Finding Duplicate Rows in SQL Server, First, define criteria for duplicates: values in a single column or multiple columns. Second, write a query to search for duplicates. If you want to also delete the  To accomplish this, we’ll need to select the entire table and join that to our duplicate rows. Our query looks like this: SELECT a.*. FROM users a JOIN (SELECT username, email, COUNT(*) FROM users GROUP BY username, email HAVING count(*) > 1 ) b ON a.username = b.username AND a.email = b.email ORDER BY a.email.

You can use exists :

select t.*
from table t
where exists (select 1  
              from table t1 
              where t1.Forename = t.Forename and t1.Surname = t.Surname and 
                    t1.DateofBirth = t.DateofBirth and t1.id <> t.id
             )

Finding Duplicates with SQL, Finding Duplicates with SQL was first published on October 06, 2004. In Access I could use a group by option called LAST. no such feature in SQL Server. 7 columns manes and i want to search n find out the duplicate rows depending on  The idea is to enumerate the rows for each specific group (partition by) and inside the group ordered by whatever criteria you want, then keep only rows were the new column is equal one. AMB Some guidelines for posting questions

Find and Remove Duplicate Rows from a SQL Server Table, Learn how to find and remove duplicate rows from a SQL Server Our task is to enforce uniqueness for the 'Value' column by removing duplicates. in the column which will be de-duplicated based on our requirements or  Here I show how to find duplicates and their frequency among multiple columns using the GROUP BY clause. Suppose you have data in which you need to find the duplicates in a single column (for example to find common names in a list of names) or in multiple columns (for example to find all the persons who have same name and age but reside at a different address).

How to Find Duplicate Rows With SQL, How to find duplicates in multiple columns. Someone recently asked a question similar to this on the #mysql IRC channel: I have a table with  Question: I would like to remove duplicate values from above table based on conditon " Equal value for "Time" ,"ID" and Absolute difference in "Time spent" is lower or equal than 1" as you can see in the image Rows highlighted falls in this category.

Finding Duplicate and Repeated Rows to Clean Data · Advanced , A great way to find duplicate rows is by using window functions – supported by The following query picks the email column to deduplicate, In a case where you want to pick a deduplicate row according a different criteria, In a case where you want to deduplicate on multiple columns, you can specific those columns are  Re: Countif with multiple criteria and duplicates counted once If that takes care of your original question, please select Thread Tools from the menu link above and mark this thread as SOLVED. Thanks.