When the Attunity Connect JDBC driver is used via a connection pool manager in an application server (e.g. Oracle WebLogic) there is often an option to configure an SQL statement to use for checking if the pooled connection is still connected before it is given by the application server to the application.

If this feature is used then the recommended SQL statement to specify is:
This query just returns the UTC timestamp of the server without incurring any I/O and is, therefore, very lightweight and quick.

Obviously, this query can be used via APIs other than JDBC (e.g., ODBC, OLEDB, ADO.NET).