Question

I have SQL tables:

id_details
year-month
type (only have 2 values , income and outcome)
amount

and table have row like this:

(year-month)      (type)     (amount)
 November-2012    income      50000
 November-2012    income      30000
 December-2012    income      20000
 November-2012    outcome     10000
 December-2012    outcome     50000
 December-2012    income      10000

What I want is, showing a query with result like this:

 (year-month)    (sum income)     (sum-outcome)   (sub-total balance)
 November-2012    80000             10000          70000
 December-2012    30000             50000          -20000 

finally

  total-balance = 50000

How can I do this?
or can you recommend me better tables design?

Answer 1

SELECT `year-month`,
       SUM(CASE WHEN type = 'income' THEN amount ELSE 0 END) `sum-income`,
       SUM(CASE WHEN type = 'outcome' THEN amount  ELSE 0 END) `sum-outcome`,
       SUM(amount) `sum-total balance`
FROM <JOINS>
GROUP BY `year-month`