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Michael KatzFlag for United States of America

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Retain previous data and update with new data

Hi Experts,

I have Source.Warehouse.SafetyStock, source.Warehouse.ReorderStock

and database2.Warehouse.SafetyStock, database2.Warehouse.PrevSafetyStock,database2.Warehouse.ReorderStock,database2.Warehouse.PrevReOrderStock.

What i need to happen is that database2.Warehouse.SafetyStock to always be equal to source.Warehouse.SafetyStock, database2.Warehouse.ReorderStock to always be equal to source.Warehouse.ReorderStock.

Our ERP system will update the source database and I want the database2.Warehouse.SafetyStock to be updated with this value and the PrevSafetyStock to hold the former source.Warehouse.SafetyStock...

Hopefully this makes sense
Avatar of Kevin Cross
Kevin Cross
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The tags suggest that this is in a trigger; therefore, one option is to use the DELETED and INSERTED tables. In other words, DELETED.SafetyStock is the previous, removed value; INSERTED.SafetyStock, the new. Hence, an UPDATE with a JOIN should suffice.

UPDATE tto
SET tto.SafetyStock = i.SafetyStock
  , tto.PrevSafetyStock = d.PrevSafetyStock
FROM database2.Warehouse tto
JOIN DELETED d ON d.PK = tto.PK /* e.g., Item ID */
JOIN INSERTED i ON i.PK = tto.PK /* should be same as above. */
;

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In my experience, the SET operations happen sequentially, but I showed example above as I do not believe you want to depend on the order of assignments. However, in theory, the following also should work.

UPDATE tto
SET tto.PrevSafetyStock = tto.SafetyStock
  , tto.SafetyStock = i.SafetyStock
FROM database2.Warehouse tto
JOIN INSERTED i ON i.PK = tto.PK /* e.g., Item ID */
;

Open in new window


Or have another trigger on the database2.Warehouse table that maintains the PrevSafetyStock, but it would be prudent to reduce the amount of triggers (i.e., complexity) in the process.

I hope that helps!
Avatar of Michael Katz

ASKER

Should this be a 'Instead of Insert' or 'After Update' ??

Not sure about the scripting
ASKER CERTIFIED SOLUTION
Avatar of Kevin Cross
Kevin Cross
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Thank you mwvisa1