上次的一个sql问题不知怎样做.

Question

tab_1 
(a    int  
b    int 
c    int 
) a                            b                            c 
-------------------------------------------------------------- 
3                            332                          45 
3                            133                          3    
3                            22                          345      
3                            43                          34 
3                            2                            35    
-3                            777                          35    
-3                            5                            3 
-3                            44                          32 
-3                            454                          24 
(a  的字段取绝对值) 
求解:(332*45+133*3+22*345+...)/a  方案 

Answer 1

:(332*45+133*3+22*345+...)/ABS(a )

Answer 2

select (sum(B*C)*1.0)/a from [TB] group by a