使用时需要关闭连接吗？

Question

I have the following code:

newCustomerDataSourceDataContext db = GetDataContext();
{
    var tId = from t in db._CRM_Ticket_Headers
              from p in db.CRM_Priority_LKPs
              where t.created >= fromDate &&
                  t.created < toDate &&
                  t.priorityId == p.priorityId &&
                  t.statusId == status &&
                  t.employeeUserId == csrId
              select t;
}

Do I have to close the Connection manually, if I add using , and I am using Linq as the following:

using (newCustomerDataSourceDataContext db = GetDataContext())
{
    var tId = from t in db.CRM_Ticket_Headers
              from p in db.CRM_Priority_LKPs
              where t.created >= fromDate &&
                  t.created < toDate &&
                  t.priorityId == p.priorityId &&
                  t.statusId == status &&
                  t.employeeUserId == csrId
              select t;
}

Answer 1

It depends on what you want to happen. If you use the using block, the Dispose method will be called on the context which will close the connection. However, if your application is using lazy loading, that will no longer work.

Answer 2

No, it will be closed once you are out of using block. Resources are cleaned up when you leave that block.

Should you dispose datacontect?

The short answer; no, you don't have to, but you should...

DataContext holds state (for example, a SqlConnection and pointers to the objects you have retrieved). These will eventually get cleaned up by the GC once you release all references, but some of these objects (for example, the underlying SqlConnection) may be holding resources that you typically want to release as soon as your are finished, rather than relying on the GC to clean up.

And as was mentioned it won't work nicely if you retrieve data in lazy mode