Sqlconnection. Open

 

Use sqlconnection. open () directly. If the network connection is disconnected, the following problems may occur:

"Network-related or instance-specific errors occur when you establish a connection with SQL Server. The server is not found or cannot be accessed. Verify that the Instance name is correct and SQL server is configured to allow remote connection. (Provider: TCP provider, error: 0-unable to connect because the target machine is actively rejected .)"

If you connect to the network later, an error will still be reported.
"A transmission error occurred when sending a request to the server. (Provider: Shared Memory provider, error: 0-there is no process on the other end of the MPs queue .)"

"The requested Database" testcorp "cannot be opened ". Logon Failed.
User 'sa 'Login Failed. "

This should be a buffer pool issue. NET 2.0 sqlconnection. clearpool or sqlconnection. clearallpools