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

Try this:

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 table1.id = table2.id 
       JOIN table3 ON table2.c = table3.c 
WHERE 
       description = 'string'
GROUP BY
lastname,firstname,description

Answer 2

Solution using Subquery

select t.lastname, t.firsname,sum(t.Withdrawal) Withdrawal ,sum(t.Deposit) Deposit,t.description from(
select lastname, firsname,
       isnull(case when upper(category) = 'W' then abs(principal) end,0) as Withdrawal,
       isnull(case when upper(category) = 'D' then abs(principal) end,0) as Deposit,
description
from table1 join
     table2
     on table2.id = table1.id join
     table3
     on table3.c = table2.c
where description = 'string'
)t group by t.lastname, t.firstname, t.description, t.category

Answer 3

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