How to calculate net income in Obsidian Dataview?

[AgniCh]

Good day everyone! I am faced with my complete misunderstanding of how to calculate net income.

I use this code to calculate income

table
sum(rows.Income) as Income
from "Monthly"
where Income
group by true as Income

And the following code to calculate expenses:

table
sum(rows.Expense) as Expenses
from "Monthly"
where Expenses
group by true as Expenses

In my understanding, to calculate net income, you need to use:

table
some(non null(rows.Income))-sum(nonnull(rows.Expense)) as "Cash Flow"
from "Monthly"
where Income or Expenses
group by true as "Cash Flow"

But it doesn’t work and gives an error:
"Dataview: Every row during final data extraction failed with an error; first 3:

• No implementation found for ‘number - string’"
  Although I’m sure there is no text there, I would appreciate any help

[anon45210282]

Does this fail?

```dataview
table
sum(nonnull(rows.Income))-sum(nonnull(rows.Expenses)) as "Cash Flow"
from "Monthly"
where Income or Expenses
group by true as "Cash Flow"
```

[AgniCh]

Yes, it did fail, but I was able to resolve the issue.

I am not sure why, but after using the “sum” command, the output was in text format, so I fixed it by converting the text to a number.

table
sum(nonnull(rows.Income))-number(sum(nonnull(rows.Expenses))) as "Cash Flow"
from "Monthly"
where Income or Expenses
group by true as "Cash Flow"