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 .. I want to add a 1 or an a to one of them and that will be for many other duplicates in the same column. Basically just add one number or letter to every 1 of the duplicates so there's no more duplicates.

I got this query that will update all the duplicates but not one of them. Can anyone help?

UPDATE Table1
   SET Column1 = 'a'
 WHERE exists
       (SELECT Column1 , COUNT(Column1 )
FROM Clients
GROUP BY Column1 
HAVING ( COUNT(Column1 ) > 1)
)

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

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 .

Answer 3

我认为您可以使用 TOP() 运算符而不是 row_number() 方法，它将帮助您以简单的方式更新一个

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

Answer 4

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 5

If we have this condition:

SELECT Column1 FROM Clients ORDER BY Column1

Column1
**********
Jhon
Jhon
Mike
Mike
Mike
Robert

This will work even if Column1 was duplicated n times, it will append the row number to every duplicate row except the first, try this:

BEGIN 

;WITH CTE AS 
(
    SELECT 
        ROW_NUMBER() OVER (PARTITION BY Column1 ORDER BY Column1) AS ROWNUMBER,
        Column1
    FROM Clients
)

UPDATE CTE 
SET Column1 = CONCAT(Column1, ' ', (ROWNUMBER - 1))
WHERE ROWNUMBER > 1

SELECT Column1 FROM Clients ORDER BY Column1

END 

Result:

Column1
***********
Jhon
Jhon 1
Mike
Mike 1
Mike 2
Robert

Answer 6

try this

with test as 
(
   select ROW_NUMBER() over (order by salary)rr, salary , emp_no 
   from salary
)update test set emp_no=10007 where emp_no='10002'  and rr=3

Answer 7

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 8

I had to put the with inside a from since my sql developer didnt like updating a with Copying from the answer from Nithesh

it ended up looking like this:

UPDATE Clients 
SET Column1 = 'a'
WHERE ColumnID IN (select ColumnID from 
 (  
 SELECT
       row_number() OVER(PARTITION BY Column1  ORDER BY Column1 ) AS rno,
       ColumnID FROM Clients
 )
                   where rno=2   
                  )

Answer 9

Using sub-queries might work:

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

Answer 10

update wmwhse1.sku
set descr= concat (descr,'.')
where exists
(select SKU,count (DESCR)
from wmwhse1.sku
group by descr
having (count (DESCR)>1))

all sku description is updating when I run this script.

output: only 1 row should be affected

Answer 11

I have found this solution:

My table devices already have data and the "serial" column should be unique. The "id" is a primary key. A random 6 digits value is concatenated after the original value.

UPDATE devices 
SET serial=CONCAT(serial,'_',LPAD(FLOOR(RAND() * 999999.99), 6, '0'))    
    where id in 
    (select * FROM( 
        SELECT d1.id as id 
        FROM devices as d1, devices as d2 
        WHERE d1.id <> d2.id and d1.serial=d2.serial) as subdevices
    )

Answer 12

Disclaimer:

1. Query Language: Microsoft SQL Query
2. Steps are clarified in comments like : --

Question: UPDATE last Id with 'D' where year, month is duplicate memberwise.

-- Sample Table Creation

DECLARE @TempTable TABLE
( Id INT IDENTITY (1, 1) NOT NULL, MemberId INT, for_year INT, for_month INT, for_status CHAR(1) )

-- Sample Insert
INSERT INTO @TempTable
SELECT '2', '2077', '11', 'A' UNION ALL
SELECT '2', '2077', '12', 'A' UNION ALL
SELECT '2', '2077', '12', 'A' UNION ALL
SELECT '3', '2077', '11', 'A' UNION ALL
SELECT '3', '2077', '12', 'A' UNION ALL
SELECT '3', '2077', '12', 'A' UNION ALL
SELECT '77', '2076', '10', 'A' UNION ALL
SELECT '77', '2076', '11', 'A' UNION ALL
SELECT '77', '2076', '12', 'A'

-- where expectation meets reality :) -- logic / main query
UPDATE @TempTable SET for_status = 'D' WHERE Id IN 
(
SELECT MAX(Id) FROM @TempTable GROUP BY MemberId, for_year, for_month HAVING COUNT(*)>1
)

-- Sample Select
SELECT * FROM @TempTable

Answer 13

I have found one solution:

Insert a dummy column in the table

Update the values in column and give random value

Update the row using that dummy column's value and drop the column.

Step 1 :
Alter table table_name
ADD column dummy_column

Step 2:
Update table_name
SET dummy_column = (RAND() * 10) 
where duplicate_column = duplicate_value

Step 3:
Update table_name
SET duplicate_column = new_value
where dummy_column = random_value

Step 4:
Alter table table_name
drop column dummy_column