sql - 如何将正数和负数分成各自的列？

Question

我有一个包含以下列和数据的表格:

activity_dt | activity_amt
 2009-01-01 |   -500
 2009-01-01 |    750

我可以编写一个查询来查看 activity_amt 的符号，如果为正，则将其放入贷方列，如果为负，则将其放入借方列？ (我使用的是 Sybase)

activity_dt | debits | credits
 2009-01-01 |  -500  |   750

Answer 1

select activity_dt, 
    sum(case when activity_amt < 0 then activity_amt else 0 end) as debits, 
    sum(case when activity_amt > 0 then activity_amt else 0 end) as credits
from the_table
group by activity_dt
order by activity_dt