public List<Map<String,String>> queryMapValues(Dao dao,  String table, Condition cnd) {
        Sql sql= Sqls.create("select * from $table");
        if (cnd!=null){
            sql= Sqls.create("select * from $table"+cnd.toString());
        }
        sql.vars().set("table",table);
        sql.setCallback(new SqlCallback() {
            List<Map<String,String>> list=new LinkedList<>();
            public Object invoke(Connection conn, ResultSet rs, Sql sql) throws SQLException {
                Map<String,String> map = new LinkedHashMap<>();
                while (rs.next()) {
                    String name=rs.getCursorName();
                    map.put(name, rs.getString(name));
                }
                list.add(map);
                return list;
            }
        });
        dao.execute(sql);
        List<Map<String,String>> list=(List<Map<String,String>>)sql.getResult();
        System.gc();
        return list;
    }

执行上述函数，在rs.getCursorName()时报错，如下：

Caused by: java.sql.SQLException: Positioned Update not supported.
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:897)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:886)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
	at com.mysql.jdbc.ResultSetImpl.getCursorName(ResultSetImpl.java:1966)
	at com.alibaba.druid.filter.FilterChainImpl.resultSet_getCursorName(FilterChainImpl.java:962)
	at com.alibaba.druid.filter.FilterAdapter.resultSet_getCursorName(FilterAdapter.java:1553)
	at com.alibaba.druid.filter.FilterChainImpl.resultSet_getCursorName(FilterChainImpl.java:960)
	at com.alibaba.druid.proxy.jdbc.ResultSetProxyImpl.getCursorName(ResultSetProxyImpl.java:389)
	at com.alibaba.druid.pool.DruidPooledResultSet.getCursorName(DruidPooledResultSet.java:421)
	at cn.wizzer.app.stargis.util.QueryEx$4.invoke(QueryEx.java:152)
	at org.nutz.dao.impl.sql.NutSql.onAfter(NutSql.java:136)
	at org.nutz.dao.impl.sql.run.NutDaoExecutor._runSelect(NutDaoExecutor.java:277)
	at org.nutz.dao.impl.sql.run.NutDaoExecutor.exec(NutDaoExecutor.java:53)
	... 77 more