Question

I have a MS SQL table that I don’t have any control over and I need to write to. This table has a int primary key that isn’t automatically incremented. I can’t use stored procs and I would like to use Linq to SQL since it makes other processing very easy.

My current solution is to read the last value, increment it, try to use it, if I get a clash, increment it again and retry.

Something along these lines:

var newEntity = new Log() {     ID = dc.Logs.Max(l => l.ID) + 1,     Note = 'Test'        };  dc.Logs.InsertOnSubmit(newEntity);  const int maxRetries = 10; int retries = 0;  bool success = false; while (!success && retries < maxRetries) {                    try     {                                                                    dc.SubmitChanges();         success = true;     }     catch (SqlException)     {         retries++;         newEntity.ID = dc.Logs.Max(l => l.ID);                       } }            if (retries >= maxRetries) {     throw new Exception('Bummer...'); } 

Does anyone have a better solution?

EDIT: Thanks to Jon, I simplified the max ID calculation. I was still in SQL thinking mode.

Answer 1

That looks like an expensive way to get the maximum ID. Have you already tried

var maxId = dc.Logs.Max(s => s.ID); 

? Maybe it doesn’t work for some reason, but I really hope it does…

(Admittedly it’s more than possible that SQL Server optimises this appropriately.)

Other than that, it looks okay (smelly, but necessarily so) to me – but I’m not an expert on the matter…