A cursor-Name refers to a cursor. No SQL language command exists to assign a name to a cursor. Instead, you use the JDBC API to assign names to cursors or to retrieve system-generated names. For more information, see the Java DB Developer's Guide. If you assign a name to a cursor, you can refer to that name from within SQL statements.
You cannot qualify a cursor-Name.
stmt.executeUpdate("UPDATE SAMP.STAFF SET COMM = " + "COMM + 20 " + "WHERE CURRENT OF " + ResultSet.getCursorName());