Problems with SUM in mysql

Question

I have a table "Cabine" with fields "SBC750" (integer) and "Evaso" (tinyint)

The field Evaso can be 1, 0 or Null

I'm looking for the sum of all sbc750 where Evaso is NOT 1.

I tried with

select sum(sbc750) from cabine  where evaso<>1;

but the result is NULL: why???

If I use

select sum(sbc750) from cabine

I obtain 55 and if I use

select sum(sbc750) from cabine where evaso=1

I obtain 34!

So the results might be 21 and not Null. Please help me

What about SELECT SUM(sbc750) FROM cabine WHERE evaso>1 OR evaso<1 — Sari Rahal, Oct 06 '17 at 14:24
Probably related: [Is there any difference between IS NULL and =NULL](https://stackoverflow.com/questions/3777230/is-there-any-difference-between-is-null-and-null#3777250) — Lukasz Szozda, Oct 06 '17 at 14:24
I agree with Sari .. I have a feeling that with `<> 1` you are returning zero results .. Just try a `select * from cabine where evaso<>1;` to test this theory .. — Zak, Oct 06 '17 at 14:25
Yes with <>1 there is no results.. The Sari's suggestion doesn't work. The lad2025's one do. — Massimo Griffani, Oct 06 '17 at 14:29

score 1 · Answer 1 · answered Oct 06 '17 at 14:28

1

With the NULL-safe equality operator you should get the desired results:

select sum(sbc750) from cabine where not evaso<=>1;

Also see here for reference.

answered Oct 06 '17 at 14:28

MatSnow

score 1 · Answer 2 · answered Oct 06 '17 at 14:29

1

SELECT sum(sbc750) FROM cabine where evaso is null or evaso<>1;

answered Oct 06 '17 at 14:29

farbiondriven

2 Answers2