What is the best way to update columns that depend on other columns (entity framework)?

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Hi,
I'm using WPF with the MVVM pattern and Entity Framework to access data from a SQL database.
I use Entity Framework to reverse engineer the database and get entities from it.
Now I need to update some data on Table_A, which has 30 columns, but I only need the user to be able to update Column10. The problem is that Column12 depends on Column10 (Column12 = Column10 + Column11).

1 - What's the most efficient way to go? Do I have to retrieve all the columns from table A using a LINQ query? Should I create myself a new Entity in the .edmx designer? I do need the result to be an ObservableColletion so creating Anonymous queries is somewhat out of the picture..
2 - How and where would I code the piece of logic to update Column12?

What I have tried:

Getting all columns from the database, but it's not efficient..

Posted 19-Oct-16 7:23am

RuiBarreiros

Updated 21-Oct-16 11:20am

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Ruard · Answer 1 · 2016-10-21T11:20:00

Update selected fields:

You can add a new entity with only the required columns. Make sure that this partial entity is not used to add new records, unless all other columns are optional. I can imagine this entity has a key and three columns (10, 11 and 12), where you alter column10 and calculate column12.

Alternative is as described here: sql - How to update only one field using Entity Framework? - Stack Overflow[^]

Column12:

Since the fields in the entity are properties you can return the calculated value instead of the current value. Do not remove set. I must admit that I didn't test this, but this should work.

C#

public string colum12 { get { return column10 + column11;} set {} }

But why update it in code anyway? The same thing can be done in the database. I suggest you change column12 into a computed column: Specify Computed Columns in a Table[^]