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Android教程之SQlit数据库操作  (4)

来源：未知责任编辑：责任编辑发表时间:2013-12-01 14:14　点击:次

得到查询出来数据的个数。Integer n = cur.getCount();
如果想从头遍历的话：cur.moveToFirst();
如果想遍历完的话可以这么做：
                     while (!cur.isAfterLast()) {        String ss = cur.getString(0) + ", " + cur.getString(1);
        data[k++] = ss;
        cur.moveToNext();
        }

public String getString(int columnIndex)
对于当前条处理完了，想进入下一条目。moveToNext()；

code example

public String[] loadData() {
        SharedPreferences passwdfile = m_ctx.getSharedPreferences("CONDITION",
        0);
        String cond = passwdfile.getString("CONDITION", null);
        mOpenHelper = new DatabaseHelper(m_ctx);
        SQLiteDatabase db = mOpenHelper.getReadableDatabase();
        String col[] = { "order_no", "type" };
        Cursor cur = db.query("MyOrder", col, cond, null, null, null, null);
        //SELECT order_no, type FROM MyOrder WHERE type='NEW'
        Integer n = cur.getCount();
        String[] data = new String[n];
        cur.moveToFirst();
        int k = 0;
        while (!cur.isAfterLast()) {
        String ss = cur.getString(0) + ", " + cur.getString(1);
        data[k++] = ss;
        cur.moveToNext();
        }
        return data;
        }

更新：

//更新条列
        SQLiteDatabase db = mOpenHelper.getWritableDatabase();
        ContentValues cv = new ContentValues();
        cv.put("stud_no", "S288");
        cv.put("stud_name", "Linda Wang");
        db.update("Student", cv, "stud_no = 'S201'", null);

删除：
        //删除条列
        mOpenHelper = new DatabaseHelper(v.getContext());
        SQLiteDatabase db = mOpenHelper.getWritableDatabase();
        db.delete("Student", "stud_no = 'S108'", null);