Question

JSP中关于statement.executeQuery（SQL）的问题，在线等

在java代码中 有如下命令：
String T1=null;//T1是上个网页传进来的学号
String url = null;
Connection conn=null;
Statement statement=null;
ResultSet rs=null;

url = "jdbc:oracle:thin:@localhost:1521:xe";
Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
conn = DriverManager.getConnection(url, "system", "oracle");
statement = conn.createStatement();

T1 = request.getParameter("T1");

String sSql = "select * from stu where s#='" + T1+"'";
rs = statement.executeQuery(sSql);

out.println(rs.getString(1));
到这里没有问题，下面：
sSql = "select * from quarterInfo where s# ='"+ T1+"'";//查询住宿信息
rs = statement.executeQuery(sSql);
out.println(rs.getString(1));//报错

是不是executeQuery（）方法只能执行一次？？？为什么？该怎么解决？

Answer 1

要next一下，你这里只有一条记录直接调用rs.next();
String sSql = "select * from stu where s#='" + T1+"'";
rs = statement.executeQuery(sSql);

rs.next();

out.println(rs.getString(1));
到这里没有问题，下面：
sSql = "select * from quarterInfo where s# ='"+ T1+"'";//查询住宿信息
rs = statement.executeQuery(sSql);
rs.next();
out.println(rs.getString(1));//报错

Answer 2

By default, only one ResultSet object per Statement object can be open at the same time.
一个Statement只能打开一个resultSet，所以先把rs close掉 再executeQuery

Answer 3

rs.close();
sSql = "select * from quarterInfo where s# ='"+ T1+"'";//查询住宿信息
rs = statement.executeQuery(sSql);
out.println(rs.getString(1));
使用s.close(),把前面那个结果集给关闭~