Calculation in SELECT oracle

Question

Good morning. I need to calculate between values that are stored in my BD, these values are marked with the + sign and - in their respective tables. I wonder if there is any way to make through a single SQL command I make these account: Sum all values that have the +signal; Sum all values that have the -signal; Decrease the result of each other;

The SQL command I’ve made so far is:

select sum(valeve) as valor from R046VER                                
            where numemp = 404 and numcad = 4170 and codcal = 1136 and              
            codeve in (select codeve from R008INC where incfgm in('+', '-') and codtab = 1) and         
            tabeve = 1 and codeve not in(select codeve from R008EVC where codtab = 1            
            and crteve in('31B','31C','31E','31F','31G','31H','31I','31J','31M','39Z','39Z','39Z','49Z','50A','50F'))

Answer 1

Use the Decode and multiply by the value

select sum(decode(incfgm,'+',1,'-',-1,0)*valeve) as valor 
from R046VER  
where numemp = 404 
and numcad = 4170 
and codcal = 1136 
and codeve in (select codeve 
               from R008INC 
               where incfgm in('+', '-') 
               and codtab = 1) 
and tabeve = 1 
and codeve not in(select codeve 
                  from R008EVC where codtab = 1            
                  and crteve in ('31B','31C','31E','31F',
                                 '31G','31H','31I','31J',
                                 '31M','39Z','39Z','39Z',
                                 '49Z','50A','50F'))