android开发第五天sqlite数据库操作

public class DBHelper extends SQLiteOpenHelper {
    /**
     * 数据库名称
     */
    private static final String DB_NAME="mydb.db";
    /**
     * 数据库版本
     */
    private static final int DB_VERSION=1;
    public DBHelper(Context context, String name, CursorFactory factory,
            int version) {
        super(context, name, factory, version);
    }
    public DBHelper(Context context) {
        this(context,DB_NAME,null,DB_VERSION);
    }
    /**
     * 创建数据库
     */
    public void onCreate(SQLiteDatabase db) {
        String sql="create table customers(id integer primary key autoincrement,name varchar(20),age int)" ;
        db.execSQL(sql);
    }

    /**
     * 用于升级
     */
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
        
    }

}

crud操作

public class CRUD {
    DBHelper helper;

    public CRUD(Context ctx) {
        helper = new DBHelper(ctx);
    }

    /**
     * insert操作
     */
    public void insert(String name, int age) {
        String sql = "insert into customers(name,age) values(?,?)";
        SQLiteDatabase db = helper.getWritableDatabase();
        db.execSQL(sql, new Object[] { name, age });
    }
    /**
     * update操作
     */
    public void update(String name, int age,int id){
        String sql = "update customers set name = ? , age = ? where id = ?" ;
        SQLiteDatabase db = helper.getWritableDatabase();
        db.execSQL(sql, new Object[]{name,age,id});
    }
    
    /**
     * delete操作
     */
    public void delete(int id){
        String sql = "delete from customers where id = ?" ;
        SQLiteDatabase db = helper.getWritableDatabase();
        db.execSQL(sql, new Object[]{id});
    }
    /**
     * 查询所有客户信息
     */
    public List<Object[]> findAll(){
        List<Object[]> list = new ArrayList<Object[]>();
        Object[] o = null ;
        String sql = "select * from customers" ;
        SQLiteDatabase db = helper.getWritableDatabase();
        Cursor cur = db.rawQuery(sql, null);
        while(cur.moveToNext()){
            o = new Object[3];
            o[0] = cur.getInt(cur.getColumnIndex("id"));
            o[1] = cur.getString(cur.getColumnIndex("name"));
            o[2] = cur.getInt(cur.getColumnIndex("age"));
            list.add(o);
        }
        cur.close();
        return list ;
    }
}