Question

我在Dynamodb中创建了具有以下详细信息的表

class OrderStatusIndex(GlobalSecondaryIndex):
    class Meta:
        index_name = 'OrderStatusIndex'
        read_capacity_units = 2
        write_capacity_units = 1
        projection = AllProjection()
    order_status = NumberAttribute(hash_key=True)
    created_on = UnicodeAttribute(range_key=True)


class Order(Model):

    class Meta:
        table_name = 'order'
        host = 'http://localhost:8000'
        read_capacity_units = 2
        write_capacity_units = 1

    order_id = NumberAttribute(hash_key=True)
    order_status = NumberAttribute(hash_key=True)
    created_on = UnicodeAttribute(range_key=True)
    order_status_index = OrderStatusIndex()

现在我想根据特定日期获得的订单状态进行查询如果我执行mysql查询，这将如下所示

select *from order where order_status = 0 and created_on >= start_date and created_on <=end_date

我们可以使用pynamodb在Dynamodb中实现同样的目标

Answer 1

试试这个：

private void getUserName(String startedBy, TextView textView) {
    mProfileRef=database.getReference("Profile").child(startedBy).child("UserDetails").child("userName");
    mProfileRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            userName = dataSnapshot.getValue(String.class);
            textView.setText(userName);
            Log.i(TAG, "onDataChange: "+userName);

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

指向for order_item in Order.scan(Order.order_status == 0 & (Order.created_on >= start_date) & (Order.created_on <= end_date)): print(order_item) API doc的链接：

http://pynamodb.readthedocs.io/en/latest/api.html#pynamodb.models.Model.scan

您可以参考以下链接，了解如何在pynamodb查询中使用条件表达式。

https://pynamodb.readthedocs.io/en/latest/batch.html#query-filters

https://pynamodb.readthedocs.io/en/latest/conditional.html#condition-expressions

希望这有帮助。

对于大于和小于运算符的日期属性的Dynamodb查询

1 个答案: