Most efficient way to update with LINQ to SQL

Pranay Rana picture Pranay Rana · May 20, 2010 · Viewed 25.2k times · Source

Can I update my employee record as given in the function below or do I have to make a query of the employee collection first and then update the data?

  public int updateEmployee(App3_EMPLOYEE employee)
  {
      DBContextDataContext db = new DBContextDataContext();
      db.App3_EMPLOYEEs.Attach(employee);
      db.SubmitChanges();
      return employee.PKEY;
  }

Or do I have to do the following?

public int updateEmployee(App3_EMPLOYEE employee)
{
    DBContextDataContext db = new DBContextDataContext();
    App3_EMPLOYEE emp = db.App3_EMPLOYEEs.Single(e => e.PKEY == employee.PKEY);
    db.App3_EMPLOYEEs.Attach(employee,emp);
    db.SubmitChanges();
    return employee.PKEY;
}

But I don't want to use the second option. Is there any efficient way to update data?

I am getting this error by using both ways:

An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported.

Answer

Pranay Rana picture Pranay Rana · May 20, 2010

I find following work around to this problem :

1) fetch and update entity (I am going to use this way because it's ok for me )

public int updateEmployee(App3_EMPLOYEE employee)
{
    AppEmployeeDataContext db = new AppEmployeeDataContext();
    App3_EMPLOYEE emp = db.App3_EMPLOYEEs.Single(e => e.PKEY == employee.PKEY);
    emp.FIRSTNAME = employee.FIRSTNAME;//copy property one by one 
    db.SubmitChanges();
    return employee.PKEY;
}

2) disable ObjectTrackingEnabled as following

// but in this case lazy loading is not supported


    public AppEmployeeDataContext() : 
                    base(global::LinqLibrary.Properties.Settings.Default.AppConnect3DBConnectionString, mappingSource)
            {
                this.ObjectTrackingEnabled = false;
                OnCreated();
            }

3) Detach all the related objects

partial class App3_EMPLOYEE
{
    public void Detach()
    {
        this._APP3_EMPLOYEE_EXTs = default(EntityRef<APP3_EMPLOYEE_EXT>);
    }
}

 public int updateEmployee(App3_EMPLOYEE employee)
{
    AppEmployeeDataContext db = new AppEmployeeDataContext();
    employee.Detach();
    db.App3_EMPLOYEEs.Attach(employee,true);
    db.SubmitChanges();
    return employee.PKEY;
}

4) use Time stamp in the column

 http://www.west-wind.com/weblog/posts/135659.aspx

5) Create stored procedure for updating your data and call it by db context