Question

I have a DB Table with a date and a field called posneg, the 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.

Answer 1

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