获取 SQLite 中列值的总和 [英] Getting sum total of column values in SQLite

问题描述

我在 SQLite 中有一个具有这种结构的表:

I have a table in SQLite with this structure:

 String CREATE_TOTAL_PRICE = "CREATE TABLE " + TOTAL_PRICE + "("
                + KEY_TPID + " INTEGER PRIMARY KEY,"
                + KEY_TPRICE + " REAL" + ")";

我正在尝试获取 KEY_TPRICE 列的所有列值的总和.我正在使用这种似乎有效的方法:

I am trying to get the sum total of all column values of column KEY_TPRICE. I am using this method which seems to work:

 public int getTotalOfAmount() {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor c = db.rawQuery("SELECT SUM(total_price) FROM " + TOTAL_PRICE, null);
        c.moveToFirst();
        int i = c.getInt(0);
        c.close();
        return i;
    }

但是当显示值时问题就来了.

But the problem comes when the value is being displayed.

你看到我输入的数据为 50.01,5.5，当得到总和时，我得到 55，但事实并非如此.

You see i have data input as 50.01,5.5 and when getting the sum total i get 55 which is not really the case.

当我在外部运行查询时，实际总数是 55.51.

The real total is 55.51 when i run the query externally.

我已经尝试将 REAL,INTEGER, FLOAT,DOUBLE 设置为我的列数据类型，但仍然

I have tried setting REAL,INTEGER, FLOAT,DOUBLE as my column data type but still

究竟是什么对我的数字进行四舍五入?请协助我提出建议.

What exactly is rounding up my figures? Please asssist me with suggestions.

推荐答案

我认为你收到 55 是因为你把它读成int"

I think you are receiving 55 because you are reading it as "int"

int i = c.getInt(0);

这就是它被转换"为 int (55) 的原因.

That's why it is being "converted" to int (55).

根据问题 https://stackoverflow.com/a/17947203/4860513 ，似乎 SUM()将返回与您正在阅读的列格式相同的数字.因此，尝试读取双精度/浮点数并分享结果:

According to question https://stackoverflow.com/a/17947203/4860513 , it seems that SUM() will return a number in the same format of the column that you are reading. So, try it to read is a double/float and share the result:

 float i = c.getFloat(0);
 double i = c.getDouble(0);

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