java - 如何从 JavaDB 读取数据

Question

我尝试创建一个简单的 Java 应用程序来从 JavaDB 读取数据。目的是从数据库中获取第一个“UNAME”变量并将其分配给“user”变量并打印它。

package giris;

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

/**
 *
 * @author Ibrahim
 */
public class Giris {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        String user = "";

        System.out.println("hello world");
        try 
        { 
            System.out.println("connecting to database");    
            Connection con = DriverManager.getConnection("jdbc:derby://localhost:1527/deneme", "ASD", "asd");
            System.out.println("succesfully connected");
            PreparedStatement pr = con.prepareStatement("select UNAME from ASD.Table1");

            ResultSet rs = pr.executeQuery();

            while(rs.next())
            {

            user = rs.getString(0);
            }
        }
        catch(Exception e)
        {
            System.err.println("error");
        }
        System.out.println(user);
    }

}

This is how my DB looks like

但是，当我运行应用程序时，输出如下:

run:
hello world
connecting to database

error
BUILD SUCCESSFUL (total time: 0 seconds)

Answer 1

缺少加载驱动类逻辑，请添加

Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance();

将此 derbyclient-10.2.2.0.jar 添加到类路径

希望对你有帮助