Check out example codes for "Update data in db .net". It will help you in understanding the concepts better.

Code Example 1

// Query the database for the row to be updated.
var query =
    from ord in db.Orders
    where ord.OrderID == 11000
    select ord;

// Execute the query, and change the column values
// you want to change.
foreach (Order ord in query)
    ord.ShipName = "Mariner";
    ord.ShipVia = 2;
    // Insert any additional changes to column values.

// Submit the changes to the database.
catch (Exception e)
    // Provide for exceptions.

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