作法：以唯讀形式擷取資訊

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不想要變更資料時，可以搜尋唯讀結果以增加查詢效能。

將 ObjectTrackingEnabled 設定為 false，即可實作唯讀處理。

注意

ObjectTrackingEnabled 設定為 false 時，DeferredLoadingEnabled 會隱含地設定為 false。

範例

下列程式碼會擷取員工雇用日期的唯讀集合。

Northwnd db = new Northwnd(@"c:\northwnd.mdf");

db.ObjectTrackingEnabled = false;
IOrderedQueryable<Employee> hireQuery =
    from emp in db.Employees
    orderby emp.HireDate
    select emp;

foreach (Employee empObj in hireQuery)
{
    Console.WriteLine("EmpID = {0}, Date Hired = {1}",
        empObj.EmployeeID, empObj.HireDate);
}

Dim db As New Northwnd("c:\northwnd.mdf")

db.ObjectTrackingEnabled = False
Dim hireQuery = _
    From emp In db.Employees _
    Select emp _
    Order By emp.HireDate

For Each empObj As Employee In hireQuery
    Console.WriteLine("EmpID = {0}, Date Hired = {1}", _
            empObj.EmployeeID, empObj.HireDate)
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