Question

所以我有一个主表产品，其中有一个ID作为主键。我想使用此ID链接到另一个表，其中包含此主键ID的多个副本。问题是，当我加入时，我会得到很多重复的值。

这是我的SQL语句：

import java.applet.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;

import javax.swing.*;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.Clip;


public class StackerMain extends Applet implements Runnable, KeyListener,
MouseListener, MouseMotionListener{

    //ADD MUSIC HERE//


    /////////////////
    //public StackerBlocks((RectangularShape s, Color c, int n, int rn, int x, int w, int h, int lr, int r){
    private StackerBlocks block1;

    private boolean gameOver;
    private int score;
    private boolean movingLeft;
    private boolean movingRight;

    private Thread stackerAnimator;
    private int delay;
    public int blockHeight = this.getSize().height/10;
    public int blockWidth = this.getSize().width/10 ;
    String playerName;

    public void init(){
        //Put Music Here

        ///////////////
        playerName = JOptionPane.showInputDialog(this, "Your Name");

        block1 = new StackerBlocks(new Rectangle2D.Double(), Color.MAGENTA, 
                3, 5, 500, blockWidth, blockHeight, -1, 1);

        delay = 200 * block1.getRowNum();

        this.setFocusable(true);
        this.addKeyListener(this);
        this.addMouseListener(this);
        this.addMouseMotionListener(this);

        score = 0;
        gameOver = false;
        movingLeft = true;
        movingRight = false;

    }

    public void start(){
        stackerAnimator = new Thread(this);
        stackerAnimator.start();
    }

    public void stop(){
        stackerAnimator = null;
    }

    public void paint(Graphics g){
        Graphics2D g2 = (Graphics2D) g;
        if (!gameOver){
            g2.setColor(block1.getColor());
            g2.fill(block1.getShape());
            g2.draw(block1.getShape());

            g2.setFont(new Font("Times New Roman", Font.BOLD, 20));
            g2.drawString("" + playerName + ": " + score, 5, 15);

        }
        else{
            g2.drawString("GAME OVER, Score: " + score, this.getWidth()/2 - 10, this.getHeight()/2 - 8);
        }
    }

    public void run(){
        while(Thread.currentThread() == stackerAnimator && !gameOver){
            block1.moveShape();
            if (movingLeft){
                block1.setX(block1.getX() - block1.getWidth());
                if (block1.getX() <= 0){
                    block1.setX(0);
                    movingLeft = false;
                    movingRight = true;
                    block1.changeHorizontalDirection();
                }
            }

            if (movingRight){
                block1.setX(block1.getX() + block1.getWidth());
                if (block1.getX() + block1.getWidth() >= this.getWidth()){
                    block1.setX(this.getWidth() - block1.getWidth());
                    movingRight = false;
                    movingLeft = true;
                    block1.changeHorizontalDirection();
                }
            }
            repaint();

            try{
                Thread.sleep(delay);
            }
            catch(InterruptedException e){
                break;
            }

        }
    }

    public void keyPressed(KeyEvent e){
        if (e.getKeyCode() == KeyEvent.VK_SPACE){
            if (movingRight){
                movingRight = false;
                block1.setRun(0);
            }
            if (movingLeft){
                movingLeft = false;
                block1.setRun(0);
            }
        }
    }

    @Override
    public void keyReleased(KeyEvent k) {

    }

    @Override
    public void mouseDragged(MouseEvent e) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseMoved(MouseEvent e) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseClicked(MouseEvent e) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseEntered(MouseEvent e) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseExited(MouseEvent e) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mousePressed(MouseEvent e) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseReleased(MouseEvent e) {
        // TODO Auto-generated method stub

    }



    @Override
    public void keyTyped(KeyEvent e) {
        // TODO Auto-generated method stub

    }


}

这是我当前的结果集：

http://i.imgur.com/MGFJRKu.png

我正在寻找类似这样的东西（其中空格为空或空）： http://i.imgur.com/hf8tq9k.png

是否可以不用多个select语句？

Answer 1

第二张图片中显示的输出不是一整套规范化的数据库记录。他们中的大多数人并不是自己的意思，因为他们缺少大部分数据。

看起来你要做的是让你的查询输出在显示时看起来更好，但这是正在进行显示的程序的工作，而不是SQL查询。

例如，您可以将SQL数据加载到Excel电子表格中，然后使用条件格式隐藏额外的重复条目（有关如何执行此操作的示例，请参阅：http://www.techrepublic.com/blog/windows-and-office/a-quick-trick-for-hiding-duplicate-excel-values/）

连接表，其中一个具有重复值的外键

1 个答案: