Metacat

    /**

     * Get the pid of the head (current) version of objects match the specified sid.

     * DataONE defines the latest version as "current" if the object in question has 

     * a matching SID and no value in the "obsoletedBy" field, regardless if it is "archived" or not.

     * @param sid specified sid which should match.

     * @return the pid of the head version. The null will be returned if there is no pid found.

     */

    public Identifier getHeadPID(Identifier sid) {

        Identifier pid = null;

        if(sid != null && sid.getValue() != null && !sid.getValue().trim().equals("")) {

            logMetacat.debug("getting pid of the head version for matching the sid: " + sid.getValue());

            String sql = "select guid from systemMetadata where obsoleted_by is null and series_id = ?";

            DBConnection dbConn = null;

            int serialNumber = -1;

            try {

                // Get a database connection from the pool

                dbConn = DBConnectionPool.getDBConnection("IdentifierManager.getHeadPID");

                serialNumber = dbConn.getCheckOutSerialNumber();

                // Execute the insert statement

                PreparedStatement stmt = dbConn.prepareStatement(sql);

                stmt.setString(1, sid.getValue());

                ResultSet rs = stmt.executeQuery();

                if (rs.next()) 

                {

                    pid = new Identifier();

                    pid.setValue(rs.getString(1));

                } 

            } catch (SQLException e) {

                logMetacat.error("Error while get the head pid for the sid "+sid.getValue()+" : " 

                        + e.getMessage());

            } finally {

                // Return database connection to the pool

                DBConnectionPool.returnDBConnection(dbConn, serialNumber);

            }

        }

        return pid;

    }