Update List into database

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Dear all,
I create a class Emp with properties same columns name of a table in database. Then i declare a List as

VB

Dim lst As New List(Of Emp)

.
I run project and insert, update, delete items in lst. I want to save data which has changed into table in database in one time.
Pls help me!

P/S: I am using LINQ to do.

Posted 31-May-12 2:54am

Nguyễn Minh Phúc

Updated 31-May-12 2:55am

v2

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Dave Kreskowiak · Answer 1 · 2012-05-31T03:50:00

Then you'll have to write the code to check each record against the one stored in the database, then take appropriate action. You won't be able to use LINQ to do this.

You might want to add some kind of "dirty" flag to your Emp class as well as a field that explains what was done to the object, such as Added, Deleted, Changed. Then you could quickly scan the object list and determine what has to be done for each record, if anything, to sync it up with the database. This would prevent you from having to consult the database for every single record in the List.

Since your Emp class is just a direct reflection of the fields in a database, you could have done the same job with a DataTable instead and just used a DataAdapter object to do all the work for you.

Nguyễn Minh Phúc · Answer 2 · 2012-05-31T04:13:00

Thanks much!
I code here:

VB

For i As Integer = 0 To lst.Count - 1
    Dim t = New Emp() With
        {
            .Code= lst.Item(i).Code,
            .Name = lst.Item(i).Name,
        }
    db.Emp.Attach(t, True)
    db.Refresh(Data.Linq.RefreshMode.KeepCurrentValues, t)
Next
db.SubmitChanges()

It show error: Cannot add an entity with a key that is already in use

Update List into database

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