Question

我正在使用sqlite数据库，在该数据库中，我确定已正确插入sqlite。现在我正在使用游标从sqlite获取数据，但是当我将数据设置为Texview时，我的应用程序崩溃了。这是我的桌子：这是我的数据库代码：

SQLiteDatabase db = this.getReadableDatabase();
    String query = "SELECT * FROM " + PRODUCT_TABLE + " WHERE ID = 23";
    Cursor cursor = db.rawQuery(query,null);
    return cursor;

这是我的光标代码：

Cursor cursor = dbHelper.getCheckOutProduct(Id);
        if (cursor != null && cursor.getCount() > 0) {
            do {
                int proId = cursor.getInt(cursor.getColumnIndex("ID"));
                int addressId = cursor.getInt(cursor.getColumnIndex("Price"));
                int paymentTypeID = cursor.getInt(cursor.getColumnIndex("Quantity"));
                int customerID = cursor.getInt(cursor.getColumnIndex("ProductID"));
                Log.e("ProductId",String.valueOf(proId));
            }while (cursor.moveToNext());
        }

我在哪里弄错了？

Answer 1

     if (cursor != null && cursor.getCount() > 0) {
           cursor.moveToFirst();
                do {
                    int proId = cursor.getInt(cursor.getColumnIndex("ID"));
                    int addressId = cursor.getInt(cursor.getColumnIndex("Price"));
                    int paymentTypeID = cursor.getInt(cursor.getColumnIndex("Quantity"));
                    int customerID = cursor.getInt(cursor.getColumnIndex("ProductID"));
                    Log.e("ProductId",String.valueOf(proId));
                }while (cursor.moveToNext());
            }

Answer 2

SQLiteDatabase db = this.getReadableDatabase();
    String query = "SELECT * FROM " + PRODUCT_TABLE + " where id = 23";
    Cursor cursor = db.rawQuery(query,null);
    return cursor;

我猜这是正确的查询

Answer 3

您将从哪里存储从游标检索到的值？为了简便起见，您可以创建一个具有必需属性的模型，并一个一个地设置它，然后返回如下列表：

Cursor cursor = dbHelper.getCheckOutProduct(Id);
List<Model> values = new ArrayList<>();
    if (cursor != null && cursor.getCount() > 0) {
        do {
            int proId = cursor.getInt(cursor.getColumnIndex("ID"));
            int addressId = cursor.getInt(cursor.getColumnIndex("Price"));
            int paymentTypeID = cursor.getInt(cursor.getColumnIndex("Quantity"));
            int customerID = cursor.getInt(cursor.getColumnIndex("ProductID"));

            Model model = new Model();
            model.setProdId(prodId);
            //just like above line set other desired values.                
            values.add(model);
            Log.e("ProductId",String.valueOf(proId));
        }while (cursor.moveToNext());
    }

    return values;

希望这有助于调试问题。

如何从SQLite检索数据？

3 个答案: