如何将所选日期保存在数据库中

DatePickerDialog.OnDateSetListener startdate=new DatePickerDialog.OnDateSetListener() { 
    public void onDateSet(DatePicker view, int year, int monthOfYear, 
            int dayOfMonth) { 
        dateAndTime.set(Calendar.YEAR, year); 
        dateAndTime.set(Calendar.MONTH, monthOfYear); 
        dateAndTime.set(Calendar.DAY_OF_MONTH, dayOfMonth);                 
    } 
};  @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.addtask);       

        Button startbtn=(Button)findViewById(R.id.AddStartButton);
        startbtn.setOnClickListener(new View.OnClickListener() { 
            public void onClick(View v) { 
                new DatePickerDialog(AddTask.this,startdate, 
                        dateAndTime.get(Calendar.YEAR), 
                        dateAndTime.get(Calendar.MONTH), 
                        dateAndTime.get(Calendar.DAY_OF_MONTH)).show();             
                } 

        private DatePickerDialog.OnDateSetListener startdate = new DatePickerDialog.OnDateSetListener() {

            // onDateSet method
            public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
            String date_selected = String.valueOf(monthOfYear+1)+\" /\"+String.valueOf(dayOfMonth)+\" /\"+String.valueOf(year);
            Toast.makeText(AddTask.this, \"Selected start Date is \"+date_selected, Toast.LENGTH_SHORT).show();

            }
            };