When you are executing a method within SQL, that method might need to reuse the current connection to the database in order to execute more SQL statements. Such a connection is called a nested connection. The way for a method to get a nested connection is to issue a connection request using the connection URL.
jdbc:default:connection
URL attributes are not supported as part of this connection URL. Any URL attributes specified in a Properties object, user name, or password that are passed to a java.sql.DriverManager.getConnection() call will be ignored.