Android新建数据库和建表demo

   public  class DBHelper extends SQLiteOpenHelper{ 

	public final static String DATABASENAME ="diaryOpenHelper.db";
	public final static int DATABASEVERSION =1; 

	//创建数据库
	public
DBHelper(Context
context,Stringname,CursorFactory factory,int version){ 

		super(context, name, factory,version);
	} 

	//创建表等机构性文件 

	public void onCreate(SQLiteDatabase db){ 

		String sql ="create tablediary"+"("_id integer primary key autoincrement,"+"topic varchar(100),"+"content varchar(1000)"+")";
		db.execSQL(sql);
	} 

	//若数据库版本有更新，则调用此方法 

	public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion){

String sql = "drop table ifexists diary";
		db.execSQL(sql);
 		this.onCreate(db);

 	}
    }