SQL数据库应用系统开发数据类

import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;

//current
public class DataManagement {
	private static java.sql.Connection con=null;  
	private ResultSet resultSet=null;	
	Statement statement=null;
	private static String driver="com.microsoft.sqlserver.jdbc.SQLServerDriver";  
	private static String  url="jdbc:sqlserver://localhost:1433;databaseName=teaching"; 
	private static String user="sa",password="watchdog";  
	public static void main(String[] args) throws Exception {
		DataManagement test=new DataManagement();
		if(!test.isLink())
			System.out.println("no");
		System.out.println(DataManagement.selectIsIdfromstudents("20150101001"));

		DataManagement.con.close();
	}
	public boolean studentToDatabase(StudentInformation sInfo){
		return false;
	}
	public static boolean setStudentsInDatabase(StudentInformation temporaryStudent,StudentInformation currentStudent) throws Exception{
		DeletStudent(currentStudent.getId());
		temporaryStudent.setBaseGradeReport(currentStudent.getBaseGradeReport());
		Addstudent(temporaryStudent);
		return true;
	}
	/**
	 * �����ݿ���ɾ��һ��ѧ����Ϣ
	 * @param id ѧ��
	 * @return �Ƿ�ɹ�
	 */
	public static boolean DeletStudent(String id){
		try {
			con.createStatement().executeUpdate("DELETE FROM students WHERE studentid = '"+id+"'");
			con.createStatement().executeUpdate("DELETE FROM elective WHERE studentid = '"+id+"'");
		} catch (SQLException e) {
			return false;
		}
		return true;
	}
	public static boolean Addstudent(StudentInformation stu){
		try {
			con.createStatement().executeUpdate("insert into students values ('"
					+ stu.getId()+"','"+stu.getClassid()+"','"+stu.getName()
					+"',"+stu.getGender()+","+stu.getGraduated()+ ")");
		//	System.out.println("noooooooooooooooooooooooo1");
		} catch (SQLException e) {
			
			return false;
		}
			for(BaseGradeReport i:stu.getBaseGradeReport()){
				try {
				//	System.out.println("noooooooooooooooooooooooo");
					con.createStatement().executeUpdate("insert into elective values ('"
							+stu.getId()+"','"
									+i.getSubjectid()
									+ "',"+i.getGrade()+")");
				} catch (SQLException e) {
					System.out.println("insert into elective values ('"
							+stu.getId()+"','"
									+i.getSubjectid()
									+ "',"+i.getGrade()+")");
					
					e.printStackTrace();
				}
			}


		return true;
	}
	public static boolean Addstudent(StudentInformation temporaryStudent,StudentInformation currentStudent){
		temporaryStudent.setBaseGradeReport(currentStudent.getBaseGradeReport());
		return Addstudent(temporaryStudent);
	}
	
	public DataManagement(){
		if(!isLink())
			System.out.println("no");
	}
	/**
	 * ��ȡ���а༶
	 * @return һ����������Classes�����ArrayList
	 * @throws Exception
	 */
	public static  ArrayList<Classes> selectAllClasses() throws Exception  
	{
		ResultSet rs=null;
		ArrayList<Classes> classes=new ArrayList<Classes>();
    	try
	    {
	        rs = con.createStatement().executeQuery("select *  FROM classes");
	    }
	    catch(Exception e)
	    {
	    	throw e;
    	}
    	
    	if(rs!=null){
    		while(rs.next()){
    	    	classes.add(new Classes(rs.getString(1),rs.getString(2)));
    		}
    	}
		return classes;
	}
	/**
	 * 
	 * @return ��һ��ѧ���Ļ�����Ϣ
	 * @throws SQLException
	 */
	public static StudentInformation greateStudent() throws SQLException{
			return greateStudent(StudentInformation.START);	
	}
	/**
	 * ����һ��ѧ��
	 * @param number �ڼ���ѧ��
	 * @return һ��ѧ���Ļ�����Ϣ
	 * @throws SQLException
	 */
	public static StudentInformation greateStudent(int number) throws SQLException{
		
		StudentInformation sInfo=new StudentInformation();
		
		number=number<StudentInformation.START?1:number;
		int count=Integer.valueOf(countStudents());
		if(count==0){
			new ChildWindow().showString("û��ѧ���ˣ����½�ѧ����");
			return StudentInformation.sInfoFormat();
		}
		number=number<=count?number:count;
		System.out.print("��ǰѧ��"+number);
		
		String []str=selectStudentFromStudents(number);
		StudentInformation.number=number;
		StudentInformation.end=Integer.valueOf(countStudents());

		sInfo.setId(str[0]);
		sInfo.setClassid(str[1]);		
		sInfo.setName(str[2]);	
		sInfo.setGender(str[3]);		
		sInfo.setGraduated(str[4]);
		sInfo.setClassname(selectClassnameFromClasses(str[1]));
		
		String[] subjectid=selectSubjectidFromAlective(str[0]);
		ArrayList<BaseGradeReport> baseGradeReport=new ArrayList<BaseGradeReport>();
		
		for(int i=0;i<subjectid.length;i++){
			baseGradeReport.add(new BaseGradeReport(
					subjectid[i], 
					selectSubjectnameFromSubjects(subjectid[i]),
					selectGradeFromAlective(str[0],subjectid[i])
							));	
		}
		sInfo.setBaseGradeReport(baseGradeReport);
		return sInfo;
	}
	/**
	 * �жϼ������������ݿ������Ƿ�ɹ�
	 * @return Boolean
	 */
	public static boolean isLink(){
		try {  
	    	Class.forName(driver);   
	        }catch (ClassNotFoundException e) {  
	        	System.out.println("��������ʧ��");  
    	    }  
		try {  
	        con=DriverManager.getConnection(url,user,password); 
	        } catch (SQLException e) {  
	        	System.out.println("����ʧ��");  
	        }  
		if(con!=null)
	        return true;
		return false;
	}
	/**
	 * ͳ��ѧ������
	 * @return ѧ������
	 * @throws SQLException
	 */
	public static String countStudents() throws SQLException{
		ResultSet rs=null;
    	try
	    {
	        rs = con.createStatement().executeQuery("select count(studentid)from students");
	    }
	    catch(Exception e)
	    {
	    	throw e;
    	}
    	if(rs!=null){
    		if(rs.next())
    			return rs.getString(1);
    	}
		return "0"; 
	}
	/**
	 * ����ѧ����Ŀ�ɼ�
	 * @param id ѧ��
	 * @param subjectid �γ̺�
	 * @return �ɼ�
	 * @throws SQLException
	 */
	private static String selectGradeFromAlective(String id,String subjectid) throws SQLException{
		ResultSet rs=null;
    	try
	    {
	        rs = con.createStatement().executeQuery("select grade FROM elective where elective.studentid="
	    +"'"+id+"'"+"and elective.subjectid='"+subjectid+"'");
	    }
	    catch(Exception e)
	    {
	    	throw e;
    	}
    	if(rs!=null){
    		if(rs.next())
    			return rs.getString(1);
    	}
		return "��"; 
	}
	/**
	 * ͨ��ѧ�Ų���ѡ�޿γ̺�
	 * @param id ѧ��
	 * @return һ�������γ̺ŵ�ArrayList<String>
	 * @throws SQLException
	 */
	private static String[] selectSubjectidFromAlective(String id) throws SQLException{
		ArrayList<String> subjectid=new ArrayList<String>();
		ResultSet rs=null;
    	try
	    {
	        rs = con.createStatement().executeQuery("select subjectid FROM elective where elective.studentid="+"'"+id+"'");
	     //   System.out.println("select subjectid FROM elective where elective.studentid="+"'"+id+"'");
	    }
	    catch(Exception e)
	    {
	    	throw e;
    	}
    	if(rs!=null){
    		while(rs.next()){
    		subjectid.add(rs.getString(1)) ;
    		//System.out.println(rs.getString(1));
    	}}
  //  	System.out.println("*"+(String[])subjectid.toArray(new String[subjectid.size()]));
    	return (String[])subjectid.toArray(new String[subjectid.size()]);   	 
	}
	/**
	 * ͨ���༶����Classes����Ѱ�Ұ༶��
	 * @param classid
	 * @return �༶����
	 * @throws SQLException
	 */
	private static String selectClassnameFromClasses(String classid) throws SQLException{
		if(classid.equals("      ")){
			return null;
		}
		ResultSet rs=null;
    	try
	    {
	        rs = con.createStatement().executeQuery("select classname FROM classes where classes.classid="+"'"+classid+"'");
	        System.out.println("select classname FROM classes where classes.classid="+"'"+classid+"'");
	    }
	    catch(Exception e)
	    {
	    	throw e;
    	}
    	
    	if(rs!=null){
    		rs.next();
    		return rs.getString(1);
    	}
		return "��";
	}
	/**
	 * ��Students����Ѱ��ѧ������Ϣ
	 * @param number
	 * @return һ������ѧ��Ψһ���Ե�����
	 * @throws SQLException
	 */
	public static String[] selectStudentFromStudents(int number) throws SQLException
	{
		ResultSet rs;
    	try
	    {
	        Statement stmt=con.createStatement();
	        rs = stmt.executeQuery(
	        		"select top 1 * from (select top "+number+
	        		"* FROM students order by studentid  )as A order by A.studentid desc");
	    }
	    catch(Exception e)
	    {
    	      throw e;
    	}
    	if(rs.next()){
    		return new String[]{rs.getString(1),rs.getString(2),rs.getString(3),rs.getString(4),rs.getString(5)};
    	}
		return null;
	}
	/**
	 * ͨ���γ̴�����Subjects����Ѱ�����Ŀγ���
	 * @param subjectid  �γ̴���
	 * @return ���
	 * @throws SQLException
	 */
	public static String selectSubjectnameFromSubjects(String subjectid) throws SQLException{
		ResultSet rs=null;
    	try
	    {
	        rs = con.createStatement().executeQuery("select subjectname  FROM subjects where subjects.subjectid='"+subjectid+"'");
	    }
	    catch(Exception e)
	    {
	    	throw e;
    	}
    	if(rs!=null){
    		if(rs.next())
    			return rs.getString(1);
    	}
		return "��"; 
	}
	/**
	 * ��ȡSubjects���пγ̴���
	 * @return ����ȫ���γ̴���ArrayList<String> 
	 * @throws SQLException
	 */
	public static ArrayList<String> selectSubjectidFromSubjects() throws SQLException{
		ArrayList<String> s=new ArrayList<String>();
		ResultSet rs=null;
    	try
	    {
	        rs = con.createStatement().executeQuery("select subjectid  FROM subjects ");
	    }
	    catch(Exception e)
	    {
	    	throw e;
    	}
    	if(rs!=null){
    		while(rs.next())
    			s.add(rs.getString(1)) ;
    	}
		return s; 
	}
	/**
	 * ��ȡ���ѧ��id
	 * @return ѧ��id
	 * @throws SQLException
	 */
	public static String selectMaxid(){
		ResultSet rs=null;
	        try {
				rs = con.createStatement().executeQuery("select max(studentid)from students");
			} catch (SQLException e) {
				// TODO �Զ����ɵ� catch ��
				e.printStackTrace();
			}
		try {
			if(rs.next()){
			    if(!(rs.getString(1)==null))
				    return rs.getString(1);
			}
		} catch (SQLException e) {
			// TODO �Զ����ɵ� catch ��
			e.printStackTrace();
		}
		return "0"; 
	}
	/**
	 * ��ѯѧ���Ƿ����
	 * @return ѧ��id
	 * @throws SQLException
	 */
	public static boolean selectIsIdfromstudents(String id){
		ResultSet rs=null;
	        try {
				rs = con.createStatement().executeQuery("select count(studentid)from students  WHERE studentid = '"+id+"'");
			} catch (SQLException e) {
				// TODO �Զ����ɵ� catch ��
				e.printStackTrace();
			}
		try {
			if(rs.next()){
			    if(!(rs.getString(1).equals("0")))
				    return true;
			}
		} catch (SQLException e) {
			// TODO �Զ����ɵ� catch ��
			e.printStackTrace();
		}
		return false; 
	}
	/**
	 * �Ͽ�����
	 */
	public static void close(){
		try {
			con.close();
		} catch (SQLException e) {
			// TODO �Զ����ɵ� catch ��
			e.printStackTrace();
		}
	}

}