I'm doing a query on mysql and so far I have this
SUM(IF(val1 IS NULL, val2, val1 )) AS total
But is it possible to do something like that?
SUM(IF(val1 IS NULL, if(val2 is null, 0, val2) val1 )) AS total
Where I say that if val1 is null put val2 but before putting val2 ask again if this null to put 0
I suggest you change to COALESCE
The idea is to return the first value not null
Staying
SUM(COALESCE(val1,val2,0)) AS total
For this case val1 = null, val2 = 5 , it will return 5 because it is the first one that is not null from left to right
For the case val1 = null, val2 = null will return 0 because 0 is the first non-zero value
For the case val1 = 10, val2 = 5 will return 10 because 10 is the first non-zero value
Based on the comment
We can add a case
SUM(COALESCE(case when val1 = 0 then null else val1 end,val2,0)) AS total