某学生各门课成绩.java

经过调查分析

/*
 * 按班查询成绩.java
 *
 * Created on 2008年10月17日, 下午4:48
 */

package javaapplication1;
import java.awt.*;
import java.sql.*;
import java.util.*;
import javax.swing.*;
/**
 *
 * @author  mis06
 */
public class 某学生各门课成绩 extends javax.swing.JPanel {
    String s=null;

    /** Creates new form 按班查询成绩 */
    public 某学生各门课成绩() {
        initComponents();
    }
    
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    // <editor-fold defaultstate="collapsed" desc=" Generated Code ">//GEN-BEGIN:initComponents
    private void initComponents() {
        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jLabel2 = new javax.swing.JLabel();
        jComboBox1 = new javax.swing.JComboBox();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        jButton1 = new javax.swing.JButton();

        jLabel1.setText("\u5b66\u53f7");

        jLabel2.setText("\u67e5\u8be2\u65b9\u5f0f");

        jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "\u6309\u5347\u5e8f\u6392\u5217", "\u6309\u964d\u5e8f\u6392\u5217", "\u5e73\u5747\u6210\u7ee9", "\u6700\u9ad8\u6210\u7ee9", "\u6700\u4f4e\u6210\u7ee9" }));

        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);

        jButton1.setText("\u67e5\u8be2");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .addContainerGap()
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.TRAILING, false)
                    .add(org.jdesktop.layout.GroupLayout.LEADING, jScrollPane1)
                    .add(org.jdesktop.layout.GroupLayout.LEADING, layout.createSequentialGroup()
                        .add(jLabel1)
                        .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                        .add(jTextField1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 76, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                        .add(22, 22, 22)
                        .add(jLabel2)
                        .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                        .add(jComboBox1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                        .add(jButton1)))
                .addContainerGap(141, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE)
                    .add(jLabel1)
                    .add(jTextField1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                    .add(jComboBox1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                    .add(jButton1)
                    .add(jLabel2))
                .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED)
                .add(jScrollPane1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 268, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
                .add(165, 165, 165))
        );
    }// </editor-fold>//GEN-END:initComponents

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_jButton1ActionPerformed
   
        
     String str=jTextField1.getText();
   int flag=jComboBox1.getSelectedIndex(); 
       
     if(flag==0)
      s="SELECT  课程.课程号,课程.课程名,成绩  FROM 课程,成绩 WHERE 成绩.学号='"+str+"' AND 课程.课程号=成绩.课程号 ORDER BY 成绩 ASC";
     if(flag==1)
      s="SELECT  课程.课程号,课程.课程名,成绩  FROM 课程,成绩 WHERE 成绩.学号='"+str+"' AND 课程.课程号=成绩.课程号 ORDER BY 成绩 DESC";
     if(flag==2)
      s=" SELECT  AVG(成绩) FROM 成绩 WHERE 学号='"+str+"'";
     if(flag==3)
       s="SELECT  课程.课程号,课程.课程名,成绩  FROM 课程,成绩 WHERE 成绩.学号='"+str+"' AND 成绩=(SELECT  MAX(成绩) FROM 成绩 WHERE 学号='"+str+"') AND 课程.课程号=成绩.课程号";
    if(flag==4)
     s="SELECT  课程.课程号,课程.课程名,成绩  FROM 课程,成绩 WHERE 成绩.学号='"+str+"' AND 成绩=(SELECT  MIN(成绩) FROM 成绩 WHERE 学号='"+str+"') AND 课程.课程号=成绩.课程号";
         
        
try{
     String s1=null,s2=null;
      Statement statement;
      Connect con=new Connect();
      statement=con.con.createStatement();
     ResultSet resultSet=statement.executeQuery(s);
    
    StringBuffer results=new StringBuffer();
    ResultSetMetaData metaData=resultSet.getMetaData();
    int numberOfColumns=metaData.getColumnCount();
    
      for(int i=1;i<=numberOfColumns;i++)
       results.append(metaData.getColumnName(i)+"\t");
          results.append("\n");
     
          while(resultSet.next())
       {  
         for(int i=1;i<=numberOfColumns;i++)
          results.append(resultSet.getObject(i)+"\t");
          results.append("\n");
       }
          
          jTextArea1.setText(results.toString());
          jTextArea1.setEditable(false);
     
    }
  
        catch(SQLException sqlException){
        JOptionPane.showMessageDialog(null,sqlException.getMessage(),"Database Error",JOptionPane.ERROR_MESSAGE);
        System.exit(1);}

   catch(ClassNotFoundException classNotFound){
       JOptionPane.showMessageDialog(null,classNotFound.getMessage(),"Driver Not Found",JOptionPane.ERROR_MESSAGE);
        System.exit(1);}// TODO add your handling code here:
    }//GEN-LAST:event_jButton1ActionPerformed
    
    
    // Variables declaration - do not modify//GEN-BEGIN:variables
    private javax.swing.JButton jButton1;
    private javax.swing.JComboBox jComboBox1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration//GEN-END:variables
    
}