将ResultSet移到第一个 [英] Moving ResultSet to first

问题描述

我有一个类似于rs的结果集对象，我使用了代码片段来计算行数.

I have a resultset obejct as rs and i used the fragment of code to count the number of rows..

       while(rs.next())
           count++;

，我不得不再次使用相同的结果集来检索数据.我用的是方法

and i has to use the same resultset again to retrieve the data. I used the method

    rs.beforefirst(); 

但它不起作用...控件未进入

but it is not working... control is not entering into

   while(rs.next()){
      cid=rs.getInt(1);
      taskdate=rs.getString(2);
      tasktime=rs.getString(3);
      addr=rs.getString(4);
   }

我必须根据我的查询返回4行.但这不是???

I has to return 4 rows according to my query.. but it doesn't ???

推荐答案

结果集是仅向前的.如果要导航回第一条记录，则需要创建可滚动结果集.

Resultset is the forward only . If you want to navigate back to the first record you need to create scrollable resultset .

  // Create a scrollable result set
Statement stmt = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
    ResultSet.CONCUR_READ_ONLY);
ResultSet resultSet = stmt.executeQuery("SELECT * FROM my_table");

// Move cursor forward
while (resultSet.next()) {
  // Get data at cursor
  String s = resultSet.getString(1);
}

// Move cursor backward
while (resultSet.previous()) {
  // Get data at cursor
  String s = resultSet.getString(1);
}

// Move cursor before first record
resultSet.beforeFirst();  //required statement in this case 

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