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 denormalised constraint [Resolved]
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lappin
Posting Yak Master

182 Posts

Posted - 09/20/2011 :  05:35:52  Show Profile  Reply with Quote
Hi, I have a legacy table which has some denormalised columns showing data which is also stored in other tables. Here is a simple example tableA (with denormalised columns)
ID, PartID, PartName, ...........

and PartTable
PartID, PartName, PartLocation

TableA contains PartName - which it should not really have - but it is used in a lot of legacy code so I don't want to delete it yet. In meantime I'd like to use a constraint or change to a computed column so PartName in tableA checks /references the PartTable.

Any suggestions other than create a VIEW and modify all the legacy applications - which is my longer-term goal.

Edited by - lappin on 09/21/2011 04:57:03

visakh16
Very Important crosS Applying yaK Herder

India
52249 Posts

Posted - 09/20/2011 :  05:38:54  Show Profile  Reply with Quote
why not link them by fk. probably you can create fk with no check to ignore the values that exist currently.

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/

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lappin
Posting Yak Master

182 Posts

Posted - 09/20/2011 :  05:53:20  Show Profile  Reply with Quote
Would the FK not just check that the PartID is a valid ID? I need to check that the PartName is correct. E.g. stop this happening-
ID, PartID, PartName, ...........
1 2a Hammer,........

and PartTable
PartID, PartName, PartLocation
2a, Drill, ShelfA
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lappin
Posting Yak Master

182 Posts

Posted - 09/21/2011 :  04:56:31  Show Profile  Reply with Quote
Resolved using visakh's suggestion of FK but used the pair of columns as key. Had to create a unique constraint on the paired columns to do this. Thanks for help.
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visakh16
Very Important crosS Applying yaK Herder

India
52249 Posts

Posted - 09/21/2011 :  05:58:53  Show Profile  Reply with Quote
wc

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SQL Server MVP
http://visakhm.blogspot.com/

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