SQLite的如何使用整型来存储价格值 [英] SQLite how to use integer for storing price value

问题描述

我使用的实型保存在SQLite数据库价值，但它不返回正确值。如果我像保存几个值1.01 将返回 4.029999999999999 。
我已阅读保存价格的SQLite是最好的方法是使用整数<一个href=\"http://dba.stackexchange.com/questions/15729/storing-prices-in-sqlite-what-data-type-to-use\">type

但我不知道如何使用它。
如何存储和在这种情况下，检索的价格？
在这里，code我现在该怎么找回价：

 光标指针= NULL;
    双totalPrice = 0;
    尝试{
        光标= mDB.rawQuery（从+ Expense.TABLE_NAME +，其中+选择+ Expense.PRICE +（的strftime（
                + dateType +，+ Expense.DATE +））+=？，新的String [] {的currentdate}）;    }赶上（例外五）{
        Log.e（TAG，错误+ e.toString（））;
        e.printStackTrace（）;
    }
    为（cursor.moveToFirst（）;！cursor.isAfterLast（）; cursor.moveToNext（））{
        totalPrice + = cursor.getDouble（cursor.getColumnIndex（Expense.PRICE））;
    }
 

解决方案

当你看到它其实原因很简单。

我不知道你在什么货币，但美国承担$。

您想存储$ 1.01这是相同的101美分。你只需乘以100。

所以存放在号码前，乘以100。
当显示的数目，除以100

---

只是要添加到答案：我也想你应该存储的数字在内存中美分/整数了。因此，对于所有的工作原理，计算等，使用该整数格式。

如果用户输入$量，将其转换直线距离为整数（乘以100）。而且，只有当你需要显示它改回$。

在换句话说，将要与从数据库中不只是当

I am using real type to save price value in SQLite database but it does not return correctly value. If I save a few values like 1.01 it will return 4.029999999999999. I have read that best way to save prices in SQLite is to use integer type

But I don't know how to use it. How to store and retrieve prices in this case? Here code how I retrieve price now:

        Cursor cursor = null;
    double totalPrice = 0;
    try {
        cursor = mDB.rawQuery("select " + Expense.PRICE + " from " + Expense.TABLE_NAME + " where " + " (strftime("
                + dateType + ", " + Expense.DATE + "))" + "= ? ", new String[] { currentDate });

    } catch (Exception e) {
        Log.e(TAG, "error" + e.toString());
        e.printStackTrace();
    }
    for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) {
        totalPrice += cursor.getDouble(cursor.getColumnIndex(Expense.PRICE));
    }

解决方案

It is actually quite simple when you see it.

I don't know what currency you are in, but assume US $.

You want to store $1.01. This is the same as 101 cents. You just multiply by 100.

So before storing the number, multiply by 100. When displaying the number, divide by 100.

---

Just to add to that answer: I also think you should store the numbers in memory as cents/integers too. So for all your workings, calculations etc, use that integer format.

If a user enters a $ amount, convert it straight away into integer (multiply by 100). And only change back to $ when you need to display it.

In other words, not just when going to and from the database.

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