Selecting with two different WHERE statements - sql

Question

I'm struggling to work out how to run a select query where I'm checking for two different values at the same time, and wanting them in seperate columns.
My table example:
ID | foreignID | value | accepted
----------------------------------
1 | 1 | 5 | Y
2 | 1 | 2 | Y
3 | 1 | 4 | N
4 | 2 | 8 | Y
And what I'm trying to do is along the lines of this:
SELECT
foreignID,
SUM(value WHERE (accepted='Y')) AS sum1,
SUM(value WHERE (accepted='N')) AS sum2
FROM example
WHERE foreignID='1'
My expected results would be:
foreignID | sum1 | sum2
------------------------
1 | 7 | 4
Obviously the above code wouldn't work, it's just a half-sudo code to show what I want. Essentially I only want to check with one foreignID but then get results from several SUMs that each require their own argument.
Does anyone know of any ways in which this could be achieved, or something similar. I've tried UNION which puts it into...
foreignID | sum
1 | 7
1 | 4
... but that's not really what I'm after.
I've also seen multiple select in one sql statement which seems to be on the right track but again, that's using UNION which I don't think is ideal for my example.
I could be wrong there so please do prove me wrong if I am. I might just be overlooking something! Thanks for any help you can provide.

Answer 1

Try this:
SELECT
foreignID,
SUM(CASE WHEN accepted = 'Y' THEN value ELSE 0 END) AS sum1,
SUM(CASE WHEN accepted = 'N' THEN value ELSE 0 END) AS sum2
FROM example
WHERE foreignID='1'

Answer 2

SQL fiddle
create table test(
id int ,
foreignid int,
value int,
accepted char(1)
)
INSERT INTO test values (1,1,5,'Y');
INSERT INTO test values (2,1,2,'Y');
INSERT INTO test values (3,1,4,'N');
INSERT INTO test values (4,2,8,'Y');
select
foreignid,
sum( case when accepted='Y' then value else 0 end) as sumY
,sum( case when accepted='N' then value else 0 end) as sumN
from test
group by foreignid;

Answer 3

This is more readable than the case:
select
foreignID,
sum("value" * (accepted = 'Y')::int) sum1,
sum("value" * (accepted = 'N')::int) sum2
from example
where foreignID = '1'
The cast of the boolean to integer results in 0 or 1. Many, if not most, of the languages cast the same way. I tested in four:
C#
Console.WriteLine("{0} {1}",
7 * Convert.ToInt32(true) - 2 * Convert.ToInt32(false),
// Or shorter:
7 * (true ? 1 : 0) - 2 * (false ? 1 : 0)
);
Python
>>> 7 * True - 2 * False
7
Javascript
<script type="text/javascript">
document.write(7 * true - 2 * false);
</script>
PHP
<?php
echo 7 * true - 2 * false;
?>