SQLException:没有这样的表

Question

现在我在连接数据库时遇到了一些麻烦.我知道我正在寻找的表存在,因为当我使用命令行访问它们时,可以查询它们.

可能是一些轻微的疏忽,但我会喜欢一些帮助.

这是我连接到数据库包持久性的地方;

import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.SQLException;


public class DBRegistry {

    private static DBRegistry db = null;
    private static Connection connection = null;

    private DBRegistry() {};

    public static synchronized DBRegistry getUniqueInstance() {
        if (db == null) {
                db = new DBRegistry();
                return db;
        }
        else return db;
    }

    public synchronized Connection getDBConnection() {
            try {
                Class.forName("org.sqlite.JDBC");
                connection = DriverManager.getConnection("jdbc:sqlite:src/database/taskMan.db");
                return connection;
            } 
            catch (SQLException e) {e.printStackTrace();} 
            catch (ClassNotFoundException e) {e.printStackTrace();}
            return null;
    }

    public synchronized void closeConnection() {
        try {
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

这是我如何查询它

public void create(UUID oid, Object obj) {
    Task t = (Task)obj;
    String statement = "INSERT INTO `complexTask` (`oid`,`description`,`status`) VALUES (?, ?, ?)";
    try {
        PreparedStatement dbStatement = db.prepareStatement(statement);
        dbStatement.setString(1, oid.toString());
        dbStatement.setString(2, t.getDescription());
        dbStatement.setBoolean(3, t.getStatus());
        dbStatement.executeUpdate();
    } catch (SQLException e) {
        e.printStackTrace();
    }
}

最后是一个堆栈跟踪:

java.sql.SQLException: no such table: complexTask
    at org.sqlite.DB.throwex(DB.java:288)
    at org.sqlite.NativeDB.prepare(Native Method)
    at org.sqlite.DB.prepare(DB.java:114)
    at org.sqlite.PrepStmt.<init>(PrepStmt.java:37)
    at org.sqlite.Conn.prepareStatement(Conn.java:231)
    at org.sqlite.Conn.prepareStatement(Conn.java:224)
    at org.sqlite.Conn.prepareStatement(Conn.java:213)
    at persistence.framework.ComplexTaskRDBMapper.create(ComplexTaskRDBMapper.java:23)
    at persistence.PersistanceFacade.create(PersistanceFacade.java:49)
    at persistence.persistanceStates.NewState.commit(NewState.java:10)
    at persistence.PersistentObject.commit(PersistentObject.java:23)
    at domain.objects.Task.commitToDB(Task.java:89)
    at domain.TaskRepository.commitToDB(TaskRepository.java:60)
    at domain.TaskController.persistanceCommit(TaskController.java:97)
    at presentation.TaskControlsJPanel$3.actionPerformed(TaskControlsJPanel.java:127)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2012)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2335)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:404)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:253)
    at java.awt.Component.processMouseEvent(Component.java:6175)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
    at java.awt.Component.processEvent(Component.java:5940)
    at java.awt.Container.processEvent(Container.java:2105)
    at java.awt.Component.dispatchEventImpl(Component.java:4536)
    at java.awt.Container.dispatchEventImpl(Container.java:2163)
    at java.awt.Component.dispatchEvent(Component.java:4362)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4461)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4125)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4055)
    at java.awt.Container.dispatchEventImpl(Container.java:2149)
    at java.awt.Window.dispatchEventImpl(Window.java:2478)
    at java.awt.Component.dispatchEvent(Component.java:4362)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:604)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:275)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:200)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:185)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:177)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:138)

还有一些JUnit代码用于测量,第一次测试通过,第二次测试失败,与上面的错误类似

package test.persistence;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import persistence.DBRegistry;
import junit.framework.TestCase;

public class TestDBRegistry extends TestCase {

    public void testDBRegistryConnection() {
        Connection con =  DBRegistry.getUniqueInstance().getDBConnection();
        assertNotNull(con);
    }

    public void testTableQuery() throws SQLException {
        Connection con =  DBRegistry.getUniqueInstance().getDBConnection();
        PreparedStatement dbStatement = con.prepareStatement("SELECT COUNT(*) FROM `singleTask`");
        assertEquals("should be 1 for successful query", 1, dbStatement.executeQuery());
    }

Answer 1

我注意到在你的单元测试和你的其他代码中,你使用了表名周围的反向标记.在最新版本的sqlite中,这很好,但在较旧的版本中它没有处理我相信.您可以尝试删除表名周围的刻度线,或者可能将它们更改为常规引号而不是后退标记？

如果这不能解决它,我会检查以确保您指向正确的db文件.如果指定不存在的文件名,则不会出现错误,只会在那里创建一个新数据库.我不确定"当前目录"在您的应用程序或单元测试的上下文中是什么,但请确保它指向您认为的位置.要对此进行测试,您可以将db文件名更改为foo.db,运行单元测试,然后搜索计算机foo.db以查看其创建位置.这将告诉你你的应用程序在哪里工作.