SQL sum of 3 columns -


i know question might seem little basic stuff want make sure right syntax because line of code run often:

i want sum columns a, b , c of table "alphabet" rows have id included in in clause.

this how i'd confirmation if possible:

select sum(a + b + c) "subtotal" alphabet id in ('1','5','378');

if id not string, shouldn't quote values.

select sum(a + b + c) "subtotal" alphabet id in (1,5,378);

this should work, may may have 1 non-obvious consequence. if row has a not null , 1 of others null, row drop out of summation because null plus else null, , nulls ignored sum operator. may safer write:

select sum(a) + sum(b) + sum(c) "subtotal" alphabet id in (1,5,378);

this suffers same potential problem, less happen because entire column have null. there various dialect specific ways defend against problem if still concerned. portable painfully verbose:

select sum(       case         when null         0         else       end       +       case         when b null         0         else b       end       +       case         when c null         0         else c       end     ) "subtotal" alphabet id in (1,5,378);

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