This function provides dynamic SQL capabilities in Virtuoso PL.
    The first argument is an arbitrary SQL statement, which may contain
    parameter placeholders. The function returns as output parameters a
    SQL state, error message, column metadata and result set rows if
    the statement is a select.A stored procedure can be invoked by exec but a procedure@s
    result set will not be received in the rows output parameter but rather
    sent to the client.