How Do I collapse rows on null values in t-sql?

Question

I\'m in a weird situation with my query. My objective is to display the total deposits and withdrawals from multiple transactions for each person and display them. I am getting

Answer 1

Use conditional aggregation . . . the case is the argument to the sum():

select lastname, firsname,
       sum(case when upper(category) = 'W' then abs(principal) end) as Withdrawal,
       sum(case when upper(category) = 'D' then abs(principal) end) as Deposit, 
       description
from table1 join
     table2
     on table2.id = table1.id join
     table3 
     on table3.c = table2.c
where description = 'string'
group by lastname, firstname, description