mysql query group function as a column - mysql

Question

I need to write a query to calculate the sum of each account but the special thing that I want is to group the some of the debit of each month as a column.
So what I need is like this example:
SELECT accid "Account ID", Left(tr_date,7) "Date", SUM(debit) "Debit Sum"
FROM transactions
WHERE tr_date Between "2014-07-01" and "2014-09-30"
GROUP BY acc_id, LEFT(tr_date,7);
The result will be something like that:
Account ID Date Debit Sum
1111 2014-07 300
1111 2014-08 351
1111 2014-09 352
1123 2014-07 500
1123 2014-08 100
1123 2014-09 230
But what I was asked to have is the following result:
Account ID 2014-07 2014-08 2014-09
1111 300 351 352
1123 500 100 230
where the user chooses the dates so the number of the columns is not limited
is there any way to do this or no? thank you for any comment or answer.

Answer 1

The only way to do that is to know the dates beforehand.
SELECT accid "Account ID"
SUM(if(LEFT(tr_date,7)="2014-07",debit,0)) "2014-07"
SUM(if(LEFT(tr_date,7)="2014-08",debit,0)) "2014-09"
SUM(if(LEFT(tr_date,7)="2014-09",debit,0)) "2014-08"
FROM transactions
WHERE tr_date Between "2014-07-01" AND "2014-09-30"
GROUP BY acc_id
if you need the user to be able to choose or add columns, you'll need to build the query dinamically either with a stored procedure or another scripting language.
PD: you're treating your dates as strings and I kept that logic. It's not a good practice though