Using results from parent queries in nested select - mysql

Question

I'm sure this is a fairly trivial problem, but I'm not sure what to google to find the solution.
I have a table that looks like this:
CREATE TABLE IF NOT EXISTS `transactions` (
`name` text collate utf8_swedish_ci NOT NULL,
`value` decimal(65,2) NOT NULL,
`date` date NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_swedish_ci ROW_FORMAT=COMPACT;
I populate this by cutting and pasting data from my internet banking service.
Value can be a negative or positive value, what both date and name contain should be fairly obvious ;)
I have constructed a query to let me see my bottom line for each month:
SELECT sum(`value`) as 'change', DATE_FORMAT(`date`, '%M %Y') as 'month'
FROM `transactions`
WHERE 1
GROUP BY year(`date`), month(`date`)
Now I would like to add the total accumulated money in the account at the end of the month as an additional column.
SELECT sum(`value`) as 'change', DATE_FORMAT(`date`, '%M %Y') as 'month',
(SELECT sum(`value`) FROM `transactions` WHERE `date` <= 123) as 'accumulated'
FROM `transactions`
WHERE 1
GROUP BY year(`date`), month(`date`)
123 is not exactly what I want in there, but I do not understand how to get at the result from my DATE_FORMAT inside that subquery.
Is this even the proper way to approach the problem?
This is mostly a personal exercise (running on a very small dataset) so I'm not very concerned about performance, readable SQL is far more important.
I am running a InnoDB table on MySQL 5.0.45

Answer 1

SELECT change,
CONCAT(mymonth, ' ', myyear) AS 'month',
(
SELECT SUM(`value`)
FROM `transactions`
WHERE `date` < DATE_ADD(STR_TO_DATE(CONCAT('01.', mymonth, '.', myyear, '%D.%M.%Y'), INTERVAL 1 MONTH))
)
FROM (
SELECT sum(`value`) as 'change', YEAR(date) AS myyear, MONTH(date) AS mymonth
FROM `transactions`
WHERE 1
GROUP BY
YEAR(`date`), MONTH(`date`)
) q
You wrote that you don't cate for performance, but this syntax is not much more complex but will be more efficient (just in case):
SELECT SUM(value) AS change,
CONCAT(MONTH(`date`), ' ', YEAR(`date`)) AS 'month',
#r : = #r + SUM(value) AS cumulative
FROM (
SELECT #r := 0
) AS vars,
transactions
WHERE 1
GROUP BY
YEAR(`date`), MONTH(`date`)
ORDER BY
YEAR(`date`), MONTH(`date`)
This one will count cumulative SUM's as well, but it will count each month only once.