Update a field based on a max select query

Question

Hi
I am just learning SQL so apologies if this is simple to you guys.
I have a table called [Stock WIP Table] which has duplicates in it.  I have an [autonumber] field, a [palletid] field, and a [number5] field.  I have the select query working to show the most recent record for each palletID:
SELECT
PalletID,MAX(autonumber)
FROMdbo.[Stock
WIP Table]
GROUPBYPalletID
How do I get the query to now delete all rows that are not in the select query?
Alternatively how could I add update the [number5] field to '1' where the [autonumber] is in the select and I can  then delete all records that do not contain a '1' in [number5]
Can anyone help?
Thanks
AJ

Answer 1

Hi
I am just learning SQL so apologies if this is simple to you guys.
I have a table called [Stock WIP Table] which has duplicates in it.  I have an [autonumber] field, a [palletid] field, and a [number5] field.  I have the select query working to show the most recent record for each palletID:
SELECT
PalletID,MAX(autonumber)
FROMdbo.[Stock
WIP Table]
GROUPBYPalletID
How do I get the query to now delete all rows that are not in the select query?
Alternatively how could I add update the [number5] field to '1' where the [autonumber] is in the select and I can  then delete all records that do not contain a '1' in [number5]
Can anyone help?
Thanks
AJ
Simply this for the DELETE
DELETE t
FROM dbo.[Stock WIP Table]t
WHERE EXISTS (SELECT 1
FROM dbo.[Stock WIP Table]
WHERE PalletID = t.PalletID
AND autonumber > t.autonumber)
No need of UPDATE bit value and then deleting. just above will ensure it gets deleted in single step
another method you may use is this
DELETE t
FROM dbo.[Stock WIP Table] t
CROSS APPLY (SELECT MAX(autonumber) AS MaxID
FROM dbo.[Stock WIP Table]
WHERE PalletID = t.PalletID
)t1
WHERE t1.MaxID <> t.autonumber
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