Why only some users get the error: “Connection is busy with results for another command”

Question

I have a Delphi Application that is connected to a SQL Server db using SDAC component from DevArt, we have 200 installations of the software and only to a customer, with some us

Answer 1

The "Connection is busy with results for another command" error means that there are at least two queries that use the same connection. This problem can occur if you are using one connection in several threads. To solve the problem in this case, you should have connection (the TMSConnection component) in each thread. Also, this problem can occur if you set the TCustomMSDataSet.FetchAll property to False. When FetchAll=False, execution of such queries blocks the current session. In order to avoid blocking OLEDB creates additional session that can cause the "Connection is busy with results for another command" error. To solve the problem in this case, you should set the TMSConnection.Options.MultipleActiveResultSets property to True. The MultipleActiveResultSets property enables support for the SQL Server Multiple Active Result Sets (MARS) technology. It allows applications to have more than one pending request per connection, and, in particular, to have more than one active default result set per connection. Please note that the MultipleActiveResultSets property works only when SQL Native Client is used. Therefore, you should also set the TMSConnection.Options.Provider property to prNativeClient.