虽然表中有很多行，但JDBC ResultSet只提供一行？ [英] JDBC ResultSet is giving only one row although there are many rows in table?

问题描述

我在表中有很多行，我在我的数据库上运行相同的查询，即MySql，但java ResultSet只给出表的第一行。这是我的代码。

I am having many rows in table and I ran the same query on my database which is MySql but java ResultSet is only giving the first row of the table. Here is my code.

public ArrayList<String> getAllAlbumsName(Integer uid) {
    ArrayList<String>allAlbumsName = new ArrayList<String>();
    try {
        String qstring = "SELECT albumname FROM picvik_picture_album WHERE " +
                "uid = '" + uid + "';";

        System.out.println(qstring);
        connection = com.picvik.util.MySqlConnection.getInstance().getConnection();
        ptmt = connection.prepareStatement(qstring);
        resultSet = ptmt.executeQuery();
        if(resultSet.next()) {
            System.out.println(resultSet.getString("albumname"));
            allAlbumsName.add(resultSet.getString("albumname"));
        }

        resultSet.close();
        ptmt.close();
        connection.close();


    } catch (Exception e) {
        e.printStackTrace();
    }   
    return allAlbumsName;
}

推荐答案

if(resultSet.next()) {
            System.out.println(resultSet.getString("albumname"));
            allAlbumsName.add(resultSet.getString("albumname"));
        }

如果你想获得所有行，它应该是：

If you would like to get all rows, it should be:

while(resultSet.next()) {
        System.out.println(resultSet.getString("albumname"));
        allAlbumsName.add(resultSet.getString("albumname"));
    }

while 语句在特定条件为真时连续执行语句块

The while statement continually executes a block of statements while a particular condition is true

注意：正如@BalusC评论的那样，你的代码会引入SQL注入攻击，最好使用ptmt.set ...而不是手动构建SQL String。

Note: As @BalusC commented, your code would introduce SQL Injection attack, it is better to use ptmt.set... Instead of constructing SQL String manually.

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