I am trying to remove some duplicate date from a table called [dbo].[FactGunSales] and the column is [sale_id]. I am checking if there are duplicates with the code below which works and then the code below is the code I am having issues with as it returns no rows affected.
-- Detecting Duplicate
SELECT [sale_id], COUNT(*) TotalCount
FROM [dbo].[FactGunSales]
GROUP BY [sale_id]
HAVING COUNT(*) > 1
ORDER BY COUNT(*) DESC
GO
-- Deleting Duplicate
DELETE FROM [dbo].[FactGunSales]
WHERE [sale_id] NOT IN (SELECT MAX([sale_id])
FROM [dbo].[FactGunSales]
GROUP BY [sale_id])
GO
Any help would be great
Use not exists:
Instead, use ROW_NUMBER() or COUNT(*). Your code seems equivalent to:
WITH todelete AS (
SELECT fgs.*, COUNT(*) OVER (PARTITION BY sale_id) as cnt
FROM [dbo].[FactGunSales] fgs
)
DELETE FROM to_delete
WHERE cnt > 1;
Normally, though, you don't want to delete all duplicates. You want to keep one of them. For that, use ROW_NUMBER():
WITH todelete AS (
SELECT fgs.*, ROW_NUMBER() OVER (PARTITION BY sale_id ORDER BY sale_id) as seqnum
FROM [dbo].[FactGunSales] fgs
)
DELETE FROM to_delete
WHERE seqnum > 1;
Your query doesn't give an indication about which row to keep. This version keeps an arbitrary row. You can keep the newest or oldest or biggest or smallest or whateverest by changing the ORDER BY clause.
Your version doesn't delete anything because at least one value of sale_id is NULL. If any value returned by the subquery is NULL, then the WHERE filters out all rows. Usually, I strongly recommend using NOT EXISTS instead, but for this purpose an updatable CTE makes more sense.
You can consider using a cte and ranking the records on the basis of sale_id, and so any duplicate sale_id would have a rank=2,3,4 etc.. After that you would need to delete entries which are <> rank=1
with cte
as (select row_number() over(partition by sale_id order by sale_id) as rnk
,*
from [dbo].[FactGunSales]
)
delete
from cte
where rnk <> 1
Related
As you can see below, I'm able to select all the row_numbers that are duplicates. I identified them using a window function ROW_NUMBER()
Although I want to delete them from the database.
How can I change my code to remove the duplicates identified, as I'm currently getting an error
WITH RowNumCTE AS (
SELECT *,
ROW_NUMBER() OVER (
PARTITION BY ParcelID,
PropertyAddress,
SalePrice,
SaleDate,
LegalReference
ORDER BY
UniqueID
) row_num
FROM housing_data
)
SELECT *
FROM RowNumCTE
WHERE row_num > 1
Duplicates are identified as having a row_number greater than 1.
Thanks
I found the solution. I used
DELETE FROM housing_data
WHERE ROWID NOT IN (
SELECT MIN(ROWID)
FROM housing_data
GROUP BY ParcelID, PropertyAddress, SalePrice, SaleDate, LegalReference
);
We have a Microsoft SQL Server table [database].[dbo].[UserInAppPurchase] with this columns:
[Id]
,[UserEmail]
,[UserId]
,[PurchaseDate]
,[ProductId]
,[TransactionId]
,[OriginalTransactionId]
,[ValidationTime]
,[ValidationReceipt]
,[ValidFrom]
,[ValidTo]
,[Platfrom]
We have multiple entries with the same [TransactionID], but per TransactionID only one row should be there. Thus we would like to delete all rows with same TransactionID and keep the one with the lowest [Id].
Thanks for the help
Andreas
One nice method uses updatable CTEs:
with todelete as (
select uiap.*,
row_number() over (partition by TransactionID order by id) as seqnum
from UserInAppPurchase uiap
)
delete todelete
where seqnum > 1;
You can, of course, use other methods that are more compatible with other databases, such as:
delete uiap from UserInAppPurchase uiap
where uiap.id > (select min(uiap2.id) from UserInAppPurchase uiap2 where uiap2.TransactionID = uiap.TransactionID);
I have the following SQL select. How can I convert it to a delete statement so it keeps 1 of the rows but deletes the duplicate?
select s.ForsNr, t.*
from [testDeleteDublicates] s
join (
select ForsNr, period, count(*) as qty
from [testDeleteDublicates]
group by ForsNr, period
having count(*) > 1
) t on s.ForsNr = t.ForsNr and s.Period = t.Period
Try using following:
Method 1:
DELETE FROM Mytable WHERE RowID NOT IN (SELECT MIN(RowID) FROM Mytable GROUP BY Col1,Col2,Col3)
Method 2:
;WITH cte
AS (SELECT ROW_NUMBER() OVER (PARTITION BY ForsNr, period
ORDER BY ( SELECT 0)) RN
FROM testDeleteDublicates)
DELETE FROM cte
WHERE RN > 1
Hope this helps!
NOTE:
Please change the table & column names according to your need!
This is easy as long as you have a generated primary key column (which is a good idea). You can simply select the min(id) of each duplicate group and delete everything else - Note that I have removed the having clause so that the ids of non-duplicate rows are also excluded from the delete.
delete from [testDeleteDublicates]
where id not in (
select Min(Id) as Id
from [testDeleteDublicates]
group by ForsNr, period
)
If you don't have an artificial primary key you may have to achieve the same effect using row numbers, which will be a bit more fiddly as their implementation varies from vendor to vendor.
You can do with 2 option.
Add primary-key and delete accordingly
http://www.mssqltips.com/sqlservertip/1103/delete-duplicate-rows-with-no-primary-key-on-a-sql-server-table/
'2. Use row_number() with partition option, runtime add row to each row and then delete duplicate row.
Removing duplicates using partition by SQL Server
--give group by field in partition.
;with cte(
select ROW_NUMBER() over( order by ForsNr, period partition ForsNr, period) RowNo , * from [testDeleteDublicates]
group by ForsNr, period
having count(*) > 1
)
select RowNo from cte
group by ForsNr, period
I am writing this query to display a bunch of Names from a table filled automatically from an outside source:
select MAX(UN_ID) as [ID] , MAX(UN_Name) from UnavailableNames group by (UN_Name)
I have a lot of name duplicates, so I used "Group by"
I want to delete all the duplicates right after I do this select query..
(Delete where the field UN_Name is available twice, leave it once)
Any way to do this?
Something likes this should work:
WITH CTE AS
(
SELECT rn = ROW_NUMBER()
OVER(
PARTITION BY UN_Name
ORDER BY UN_ID ASC), *
FROM dbo.UnavailableNames
)
DELETE FROM cte
WHERE rn > 1
You basically assign an increasing "row number" within each group that shares the same "un_name".
Then you just delete all rows which have a "row number" higher than 1 and keep all the ones that appeared first.
With CTE As
(
Select uid,ROW_NUMBER() OVER( PARTITION BY uname order by uid) as rownum
From yourTable
)
Delete
From yourTable
where uid in (select uid from CTE where rownum> 1 )
Here are the columns in my table:
Id
EmployeeId
IncidentRecordedById
DateOfIncident
Comments
TypeId
Description
IsAttenIncident
I would like to delete duplicate rows where EmployeeId, DateOfIncident, TypeId and Description are the same - just to clarify - I do want to keep one of them. I think I should be using the OVER clause with PARTITION, but I am not sure.
Thanks
If you want to keep one row of the duplicate-groups you can use ROW_NUMBER. In this example i keep the row with the lowest Id:
WITH CTE AS
(
SELECT rn = ROW_NUMBER()
OVER(
PARTITION BY employeeid, dateofincident, typeid, description
ORDER BY Id ASC), *
FROM dbo.TableName
)
DELETE FROM cte
WHERE rn > 1
use this query without using CTE....
delete a from
(select id,name,place, ROW_NUMBER() over (partition by id,name,place order by id) row_Count
from dup_table) a
where a.row_Count >1
You can use the following query. This has an assumption that you want to keep the latest row and delete the other duplicates.
DELETE [YourTable]
FROM [YourTable]
LEFT OUTER JOIN (
SELECT MAX(ID) as RowId
FROM [YourTable]
GROUP BY EmployeeId, DateOfIncident, TypeId, Description
) as KeepRows ON
[YourTable].ID = KeepRows.RowId
WHERE
KeepRows.RowId IS NULL