SQL Case statements deriving new attribute

Question

I have a table with indicators of directions and based on that I need to derive a new column which tells whether its IN or Out

ORG_IN  ORG_OUT DEST_IN DEST_OUT    Direction
0   0   0   0   NULL
0   0   0   1   Out
0   0   1   0   In
0   1   0   0   Out
0   1   0   1   Out
0   1   1   0   NULL
1   0   0   0   In
1   0   0   1   NULL
1   0   1   0   In

This is the query where ill derived the direction http://sqlfiddle.com/#!4/a9f82/1

Do you think it will cover all cases in future for all the combinations. Right now I can see only above combinations. Any better way to write the sql.

Answer 1

select t.*, case ORG_IN + DEST_IN - ORG_OUT - DEST_OUT 
              when 2 then 'In'
              when 1 then 'In'
              when 0 then null
              when -1 then 'Out'
              when -2 then 'Out'
            end as Direction
from tablename t

I can't figure out any more valid combinations. However, I'd recommend a check constraint that makes sure no invalid combinations are entered:

check (ORG_IN + ORG_OUT < 2 and DEST_IN + DEST_OUT < 2)