java - jdbc 中的语句仅检索第一条记录，尽管有几条记录

Question

下面的代码迭代，while 循环，并检索所有匹配的记录:

ResultSet rs3 = st.executeQuery("select id from fbprofiles where age<=(select age from fbprofiles where id="+user+") and id not in("+user+")");
        String id;
        query = "select id from fbprofiles where age<=(select age from fbprofiles where id="+user+") and id not in("+user+")";
        System.out.println(query);
        //ResultSet rs4;

        while(rs3.next())
        {
            st = con.createStatement();
            id = rs3.getString(1);
            System.out.println("id: "+id);
            /*query = "select name from fbpages where name in(select name from pagelikes_"+id+" where name not in('"+pagesLiked.toString()+"')) and category in("+category.toString()+")";
            System.out.println(query);
            rs4 = st.executeQuery(query);
            while(rs4.next())
            {
                message += "<a href="+rs4.getString(1)+".html style=\"color:black\">"+rs4.getString(1)+"</a><br>";
                pagesLiked.append(rs4.getString(1));
            }*/
        }

输出:

id:2

id:3

但是当我删除注释时，循环仅迭代一次，结果集仅包含 1 条记录而不是 2 条记录。

我对所有查询使用了不同且相同的结果集，这也给出了仅 1 条记录的相同输出。

当我 checkin SQL 数据库(11g)时，所有查询都可以正常工作。

Answer 1

当您在同一语句上执行下一个查询时，您将关闭 rs。

public static void main(String[] args) throws SQLException, Exception {
        Connection con = ConnectionDefinition.getOracleConnection(); //my oracle connection
        String q1 = "select object_name from user_objects";      
        PreparedStatement ps = con.prepareCall(q1);
        ResultSet rs = ps.executeQuery();
        while(rs.next()){
            ResultSet rs2 = ps.executeQuery(q1);
            if(rs.isClosed()){
                System.err.println("FRIST RS IS CLOSED");
            }
        }     
        con.close();
    }