Question

目前，我正在进行类似如下的更新，因为我看不到更好的方法。我已尝试过我在博客中阅读的建议但没有工作，例如

http://msdn.microsoft.com/en-us/library/bb425822.aspx
和
http://weblogs.asp.net/scottgu/archive/2007/05/19/using-linq-to-sql-part-1.aspx

也许这些确实有用，我错过了一些观点。还有其他人和他们一起运气吗？

// please note this isn't the actual code. 
// I've modified it to clarify the point I wanted to make 
// and also I didn't want to post our code here!

public bool UpdateMyStuff(int myId, List<int> funds)
{
    // get MyTypes that correspond to the ID I want to update
    IQueryable<MyType> myTypes =
        database.MyTypes.Where(xx => xx.MyType_MyId == myId);

    // delete them from the database
    foreach (db.MyType mt in myTypes)
    {
        database.MyTypes.DeleteOnSubmit(mt);
    }

    database.SubmitChanges();

    // create a new row for each item I wanted to update, and insert it
    foreach (int fund in funds)
    {
        database.MyType mt = new database.MyType
        {
            MyType_MyId = myId,
            fund_id = fund
        };

        database.MyTypes.InsertOnSubmit(mt);
    }

    // try to commit the insert
    try
    {
        database.SubmitChanges();
        return true;
    }
    catch (Exception)
    {
        return false;
        throw;
    }
}

不幸的是，没有database.MyTypes.Update()方法，所以我不知道更好的方法。 sombody可以建议我能做什么？感谢。

..作为附注，为什么没有Update()方法？

Answer 1

嗯？

public void UpdateCustomer(int CustomerId, string CustomerName)
{
  using (MyDataContext dc = new MyDataContext)
  {
    //retrieve an object from the datacontext.
    //  datacontext tracks changes to this instance!!!
    Customer customer = dc.Customers.First(c => c.ID = CustomerId);
    // property assignment is a change to this instance
    customer.Name = CustomerName;
    //dc knows that customer has changed
    //  and makes that change in the database
    dc.SubmitChanges();
  }
}

如何使用LINQ进行更新？

1 个答案: