Update Top 1

Question

Update Top 1

Ben Wilson-179630

SSC Eights!

Points: 998
More actions
January 3, 2005 at 10:57 pm

#164112

Hi All,
I have a table with the following fields: TransactionId, AssetType, AssetDetails, Order. Primary key is TransactionId, AssetType and Order.
One of the current assetTypes is 'House'. A Transaction can have many houses (Hence order is part of the key). I am trying to update the AssetType of the first house for each transaction to 'Home' (ie where AssetType is currently = 'House' and Order is the min 'Order' where for assetType House).
What i tried to do (that didnt work) was:
UPDATE TOP 1 tbl_ApplicantAsset
SET AssetType = 'Home'
FROM Asset
WHERE (tbl_Asset.AssetType = N'House')
GROUP BY Asset.TransactionId
It seems Update Top 1 is not a valid statement...any suggestions for ways to go about this that will work ???
Thanks
Ben

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Gail Shaw SSC Guru Points: 1004504 More actions · Answer 1

I'm not sure I completely understood what you're trying to do, but the below code should be fairly close to what you're trying.

If I've missed the mark by a few miles, please post the table definitions.

Update tbl_ApplicantAsset SET tbl_ApplicantAsset = 'Home' FROM tbl_ApplicantAsset INNER JOIN

(select TransactionID, min([Order]) as minOrder from tbl_ApplicantAsset where AssetType = N'House') Filtered

On tbl_ApplicantAsset.TransactionID = Filtered.TransactionID AND tbl_ApplicantAsset.[Order] = Filtered.minOrder

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

Kenneth Wilhelmsson SSC-Dedicated Points: 30043 More actions · Answer 2

You are aware that by updating 'House' to 'Home' you are in fact also changing the Primary Key for that record? Have you carefully analyzed what the consequences of such an update would be for the integrity of your data?

/Kenneth

Ben Wilson-179630 SSC Eights! Points: 998 More actions · Answer 3

Thanks for the help guys...yu were right on the mark with the suggested code I didnt know i could do a join like that!!

I hadnt considered that I was changing the primary key, but have had a good look, and in this case, it wont have any adverse affects on the data

Thanks again!

Ben

Kenneth Wilhelmsson SSC-Dedicated Points: 30043 More actions · Answer 4

Of course I don't know your data as you do, but.... I must stress my point here.

I just want to make sure that you do realize that by doing this update, you will create a new instance (eg row) of the entity (in table) that previously didn't exist, and also by doing so, you will delete an existing instance of the entity, thereby changing the fact that it has ever existed, along with it being the 'parent' of several rows that I suppose have some relation to each other (the order differs only).

The point I'm trying to make is that you want to change the PK for some, but not for all of the registered and currently related asset records. This seems a little strange to me, that's why I'm, asking. I want you to be sure that you're not doing anything you'd later regret..

/Kenneth

Ben Wilson-179630 SSC Eights! Points: 998 More actions · Answer 5

Thanks again Kenneth...the asset table does not have any child tables, and the reason for the update is to introduce a new asset type 'Home' for all home owners (as we now wish to distinguish investment properties from homes). AS long as the new home asset is still realted to the same TransactionId, all will be well!

Richard Berman SSC Veteran Points: 209 More actions · Answer 6

Richard Berman

SSC Veteran

Points: 209

March 2, 2005 at 3:09 pm

#545041

BTW, "UPDATE TOP" will work in SQL Server 2005.

Ben Wilson-179630 SSC Eights! Points: 998 More actions · Answer 7

Cool! will be great to see what 2005 can do! Sounds like there is gonna be lots of new and useful commands...which will be good, but even more to learn!

discotech SSC Veteran Points: 214 More actions · Answer 8

Here's an alternative that should also work.

Update ta

SET ta.tbl_ApplicantAsset = 'Home'

FROM tbl_ApplicantAsset ta

where ta.tbl_ApplicantAsset = 'House'

and ta.[Order] = ( select min([t2.Order])

from tbl_ApplicantAsset t2

where t2.TransactionID = ta.TransactionID

and t2.AssetType = N'House')