Update one of 2 duplicates in an sql server database table

Question

I have got a table that got a column with duplicate values. I would like to update one of a 2 duplicate values so for example row1 = tom and row2 = tom

Answer 1

Try This with CTE and PARTITION BY

;WITH cte AS
(
  SELECT
      ROW_NUMBER() OVER(PARTITION BY Column1  ORDER BY Column1 ) AS rno,
      Column1 
  FROM Clients
)

UPDATE cte SET Column1 =Column1 +' 1 '
WHERE rno=2

Answer 2

Using sub-queries might work:

UPDATE table1
SET STATUS = 'F'
WHERE column1= 
   (SELECT (column1)
    FROM table1
    GROUP BY column1 
    HAVING (COUNT(column1 ) > 1))

Answer 3

Try this mate

UPDATE Table1 
SET Column1 = column1 +'a'   
WHERE exists(
        select row 
        from (
            SELECT 
                Column1 , 
                Row_Number() over(Partition by Column1 order by Column1) as row 
            FROM Clients
        ) as subquery 
        where subquery.row = 2
    )

Answer 4

I think you can use TOP() operator instead of row_number() method it will help you to update one in easy and simple way

UPDATE TOP ( 1 )Table1 SET Column1 = 'a';

Answer 5

Assume Table1, containing the following information:

Column1      
========  
tom        
john   
jack    
tom     
james
jane 

Notice that the first and fourth rows are identical. Here's the UPDATE command to change the name in only one of them.

UPDATE Table1 AS t1
   SET Column1 = 'jennifer'
 WHERE rrn(t1) =
       (SELECT MAX(rrn(t2))
          FROM Table1 AS t2
         WHERE Column1 = 'tom')

And the result would be

Column1      
========  
tom        
john   
jack    
jennifer
james
jane 

with RRN function you can update the last occurance of duplicate record

Answer 6

I think this simple update is what you're looking for;

UPDATE Table1 SET Column1=Column1+CAST(id AS VARCHAR)
WHERE id NOT IN (
  SELECT MIN(id) 
  FROM Table1
  GROUP BY Column1
);

Input:

(1,'A'),
(2,'B'),
(3,'A'),
(4,'C'),
(5,'C'),
(6,'A');

Output:

(1,'A'),
(2,'B'),
(3,'A3'),
(4,'C'),
(5,'C5'),
(6,'A6');

An SQLfiddle to test with.