
This signals the given SQLSTATE with the message.  The calling procedure will transfer control to the most appropriate local handler. In the absence of a local handler the procedure terminates and signals the exception in the scope where it was called from, until there either is a handler or there are no more calling procedures.  If there is no handler in the entire stack of call contexts the error is signalled to the client.
Handlers can be declared with whenever .. goto and the declare handler for construct.
See the Virtuoso/PL documentation.
