我无法按照我想要的顺序从数据库中获取值

Question

我正在尝试从数据库中获取 android 中条形图的值。

id   amount  status   month
1    3567       +      4
2    5673       -      3
3    2356       +      2
4     789       -      8
5    1789       +      8

请考虑这个 table。（对不起，我无法添加图像）。因为，我需要获取条形图的值，所以我希望在 x 轴上显示月份，在 y 轴上显示数量。条形图应该是收入与支出图表。

我应用了以下查询：

Cursor c=db1.rawQuery("select distinct month, (select sum(amount) from expenses where status like '+' group by month) as income, (select sum(amount) from expenses where status like '-' group by month)as expense from expenses", null);

我得到以下结果：

month   income   expense
4       2356       5673
3       2356       5673
2       2356       5673
8       2356       5673

而不是

month    income    expense
4        3567       null
3        null       5673
2        2356       null
8        1789       789

我希望如果有更多的行（比如说，month=4 和 status="+", amount=20），那么结果应该是 3587 而不是 3567。

感谢您的宝贵时间和帮助。

Answer 1

select distinct month, 
    (select sum(amount) from expenses where month = t.month and status like '+' group by month) as income, 
    (select sum(amount) from expenses where month = t.month and status like '-' group by month) as expense 
from expenses t

Answer 2

如果您执行子查询，您需要加入数据，因为子查询将搜索所有 table(s)。对不起，我没看到只有 1 个 table 也试试这个。

select 
   distinct month,
   (select sum(ammount) from foo as f2 where f1.month=f2.month and status='+' ) as income,
   (select sum(ammount) from foo as f3 where f1.month=f3.month and status='-') as expense
from foo f1

我无法按照我想要的顺序从数据库中获取值

I am not able to get the values from the database in the order I want

database

sqlite

union

android

bar-chart