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Asked: 2026-05-26T09:48:53+00:00

I’m fairly new to SQL, and i’m trying to make a query with simple

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I’m fairly new to SQL, and i’m trying to make a query with simple math in the Android app.
Here’s what i’m trying to do –

I have a table named allfoods, with columns named ‘calories’ and ‘size’. Here’s the query-

int tempCalories = 100;
int maxCalories = 300;
Cursor dataFoods = myDataBase.rawQuery("SELECT id FROM allfoods WHERE size <> 0 AND (" + tempCalories + " + (calories * (size / 100)) < " + maxCalories +")" , null);

Will that work?
I have some trouble testing it myself, since the returned values are too varied.

Thanks!

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1 Answer

  1. Editorial Team

    Hello tofira,

    Yes, your query will work, if you change the denominator to 100.0 in (size / 100.0).

    However, your query might return 0, as your equation:

    100 + (calories * (size / 100.0)) < 300

    will return false when the values for size and/or calories are out of range.

    Proof

    To test your query I created a table with data, and a tests view.

    Data

    To have something to test against, I created a table where the values for size ranged in steps of 1 from 1 to 1000 and calories ranged in steps of 5 from 5 to 5000, like this:

    Id  |   size    |   calories
----------------------------
1   |   1       |   5
2   |   2       |   10
3   |   3       |   15
4   |   4       |   20
5   |   5       |   25

    Test

    To test your equation, I created a view to verify each step of your equation.

    SQL

    CREATE VIEW "test" AS 
    SELECT id, size AS 'S', calories AS 'C',
    size/100.0 AS 'S/100',
    calories * (size/100.0) AS 'C*(S/100)', 
    100 + (calories * (size/100.0)) AS '100+(C*(S/100))',
    CASE WHEN (300 > (100 + (calories * (size/100.0)))) 
        THEN 'true' ELSE 'false' END AS 'Eq'
    FROM allfoods;

    Result

    Id  |  S   |  C    |  S/100  |  C*(S/100)  |  100+(C*(S/100))  |  Eq
---------------------------------------------------------------------------
62  |  62  |  310  |  0.62   |  192.2      |  292.2            |  true
63  |  63  |  315  |  0.63   |  198.45     |  298.45           |  true
64  |  64  |  320  |  0.64   |  204.8      |  304.8            |  false
65  |  65  |  325  |  0.65   |  211.25     |  311.25           |  false
66  |  66  |  330  |  0.66   |  217.8      |  317.8            |  false

    Conclusion

    Running your query against my test data would return row 1 to 63.

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