Help with sql query using case and group

I have a DB Table with a date and a field called posneg, t开发者_开发百科he value is either 'pos', 'neu' or 'neg'.

I need a result set where the posneg values are added and then grouped by date. Like this

2010-10-03    5   (on that date it could be 12 pos, 5 neu and 7 neg)
2010-10-04    -3  (on that date maybe 10 pos, 2 neu and 13 neg)
...and so on

Basically the neu doesn't matter, as you see.

---

SELECT
  date,
  posneg = SUM(
    CASE posneg
      WHEN 'pos' THEN 1
      WHEN 'neg' THEN -1
      ELSE 0
    END
  )
FROM atable
GROUP BY date

---

Try this:

SELECT date, SUM(IF(posneg='pos',1,IF(posneg='neg',-1,0))) as total
FROM table GROUP BY date

---

with tab as(

select cast('12/12/2010' as smalldatetime) as dt, 'neg' as posneg 
union all
select cast('12/12/2010' as smalldatetime) as dt, 'pos' as posneg 
union all
select cast('12/12/2010' as smalldatetime) as dt, 'pos' as posneg 
union all
select cast('12/12/2010' as smalldatetime) as dt, 'pos' as posneg 
union all
select cast('12/15/2010' as smalldatetime) as dt, 'neg' as posneg 
union all
select cast('12/15/2010' as smalldatetime) as dt, 'neg' as posneg 
union all
select cast('12/15/2010' as smalldatetime) as dt, 'pos' as posneg
)

select dt,
sum(case when posneg='pos' then 1
         when posneg='neg' then -1
         else 0 end) as total
         from tab
         group by dt