android下建立資料庫學習筆記

標籤：

##在Android中建立一個資料庫##

###步驟###

1、建立一個類繼承SQLiteOpenHelper並在類中重寫父類的構造方法、onCreate方法、onGrade方法（資料庫的版本只能升級，不能降級）

###資料庫增刪改查方法##
    public void add(View view){
        SQLiteDatabase db = sql.getWritableDatabase();
        //Random random = new Random();    
        //在資料庫中增加一條資料
        db.execSQL("insert into info (name,phone) values (?,?)", new Object[]{"張三","123456"});
        db.execSQL("insert into info (name,phone) values (?,?)", new Object[]{"李四","654321"});
        Toast.makeText(this,"add successfully!",Toast.LENGTH_SHORT).show();
        db.close();
    }
    public void delete(View view){
        SQLiteDatabase db = sql.getWritableDatabase();
        //在資料庫中刪除指定資料
        db.execSQL("delete from info where name=?", new Object[]{"張三"});
        Toast.makeText(this,"delete successfully!",Toast.LENGTH_SHORT).show();
        db.close();
    }
    public void upgrade(View view){
        SQLiteDatabase db = sql.getWritableDatabase();
        //在資料庫中修改指定資料
        db.execSQL("update info set phone=? where name=?", new Object[]{"111111","李四"});
        Toast.makeText(this,"upgrade successfully!",Toast.LENGTH_SHORT).show();
        db.close();
    }
    public void checkAll(View view){
        SQLiteDatabase db = sql.getReadableDatabase();
        //查詢資料庫並返回遊標集cursor
        Cursor cursor = db.rawQuery("select * from info", null);
        //建立List集合
        List<Person>list = new ArrayList<Person>();
        //通過while迴圈遍曆資料庫資料
        while(cursor.moveToNext()){
            Person person = new Person();
            person.setId(cursor.getInt(cursor.getColumnIndex("_id")));
            person.setName(cursor.getString(cursor.getColumnIndex("name")));
            person.setPhone(cursor.getString(cursor.getColumnIndex("phone")));
            list.add(person);
            person=null;
        }
        cursor.close();
        //遍曆List集合
        for(Person p:list){
            System.out.println(p.toString());
        }
        Toast.makeText(this,"checkAll successfully!",Toast.LENGTH_SHORT).show();
        db.close();
    }

android下建立資料庫學習筆記