在请求的时间内无法获得锁 [英] A lock could not obtained within the time requested issue

问题描述

标题是我得到的错误，当我单击加载"时，程序冻结了.我认为这是因为我正在声明中进行声明，但是从我看来，这是解决我的问题的唯一方法.通过加载，我只想重新填充患者列表，但是要做到这一点，我还需要满足他们的条件.代码有效，底部的方法就是我要修复的方法.我认为问题在于我有2条陈述要公开，但我不确定. 加载:

The title is the error I'm getting, when I click load my program freezes. I assume its because I'm doing a statement inside a statement, but from what I see its the only solution to my issue. By loading I want to just repopulate the list of patients, but to do so I need to do their conditions also. The code works, the bottom method is what I'm trying to fix. I think the issue is that I have 2 statements open but I am not sure. load:

public void DatabaseLoad()
{
    try
    {
        String Name = "Wayne";
        String Pass= "Wayne";
        String Host = "jdbc:derby://localhost:1527/Patients";
        Connection con = DriverManager.getConnection( Host,Name, Pass);
        PatientList.clear();


        Statement stmt8 = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,        
             ResultSet.CONCUR_UPDATABLE);
        String SQL8 = "SELECT * FROM PATIENTS";
        ResultSet rs8 = stmt8.executeQuery( SQL8 );
        ArrayList<PatientCondition> PatientConditions1 = new ArrayList();

        while(rs8.next())
        {
            PatientConditions1 = LoadPatientConditions();
        }

        Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,    
            ResultSet.CONCUR_UPDATABLE);
        String SQL = "SELECT * FROM PATIENTS";
        ResultSet rs = stmt.executeQuery( SQL );

        while(rs.next())
        {
            int id = (rs.getInt("ID"));
            String name = (rs.getString("NAME"));
            int age = (rs.getInt("AGE"));
            String address = (rs.getString("ADDRESS"));
            String sex = (rs.getString("SEX"));
            String phone = (rs.getString("PHONE"));

            Patient p = new Patient(id, name, age, address, sex, phone,
                PatientConditions1);
            PatientList.add(p);
       }

        UpdateTable();
        UpdateAllViews();

        DefaultListModel PatientListModel = new DefaultListModel();

        for (Patient s : PatientList) {
            PatientListModel.addElement(s.getAccountNumber() + "-" + s.getName());
        }

        PatientJList.setModel(PatientListModel);

       }

    catch(SQLException err)
    {
        System.out.println(err.getMessage());
    }


}

这是返回患者病情数组列表的方法

This is the method that returns the arraylist of patient conditions

public ArrayList LoadPatientConditions()     
{ 
    ArrayList<PatientCondition> PatientConditionsTemp = new ArrayList();
    try
    {
        String Name = "Wayne";
        String Pass= "Wayne";
        String Host = "jdbc:derby://localhost:1527/Patients";
        Connection con = DriverManager.getConnection( Host,Name, Pass);
        Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,   
            ResultSet.CONCUR_UPDATABLE);
        String SQL = "SELECT * FROM PATIENTCONDITIONS";
        ResultSet rs5 = stmt.executeQuery( SQL );

        int e = 0;
        while(rs5.next())
        {
            e++;
            String ConName = (rs5.getString("CONDITION"));
            PatientCondition k = new PatientCondition(e,ConName);
            PatientConditionsTemp.add(k);
        }   
     }
     catch(SQLException err)
     {
         System.out.println(err.getMessage());
     }

     return PatientConditionsTemp;
 }

推荐答案

遇到类似的问题. 我正在连接到本地服务器上托管的derby db. 我创建了2个同时连接:

Had a similar problem. I was connecting to derby db hosted on local server. I created 2 simultaneous connections:

• 和松鼠
• 使用 ij 工具

当连接在表上进行修改时，它首先获得特定表的锁. 仅在提交事务之后，连接才会释放此锁. 因此，如果第二个连接尝试读取/写入相同的表，则msg会提示说:
错误40XL1:在请求的时间内无法获得锁

要解决此问题，修改表的连接必须提交其事务.

希望这会有所帮助！

When a connection makes a modification on a table, it first gets a lock for the particular table. This lock is released by the connection only after committing the transaction. Thus if the second connection tries to read/write the same table, a msg prompts saying:
ERROR 40XL1: A lock could not be obtained within the time requested

To fix this, the connection which modified the table has to commit its transaction.

Hope this helps !

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