how to show week over week in sql - mysql

Question

I need to display two calculated columns of the sum of GP for one week and in the other column previous
I think my way is right but i am missing something
I am trying to get my result to be like this::
|WEEK|JP|AUS|GB|
|PREV|22|32|23|
|CUR|12|15|12|
my sql is this I believe I may need to pivot the data
SELECT
(SUM(`GP`), `gptw`)
FROM
(SELECT
`GP`,
`Country`
FROM
`Finance`
WHERE DATE >= CURDATE() - INTERVAL DAYOFWEEK(CURDATE()) + 6 DAY
AND DATE < CURDATE() - INTERVAL DAYOFWEEK(CURDATE()) - 1 DAY
GROUP BY `Country`) AS lastweeek
INNER JOIN
(SELECT
SUM(`GP`) AS `gptw`,
`Country`
FROM
Finance
WHERE DATEDIFF(NOW(), `date`) < 4
GROUP BY `Country`) AS `thisweek`

Answer 1

Nitpick: DATE is a poor choice of column name because it's a reserved SQL word.
There are four levels of logic here.
First, you need to have working logic to figure out which week each day is in.
Second, you need to select the correct range of DATE values.
Third, you need to get the GROUP BY logic right.
Fourth, you need to pivot your result set to get this week and last week into the same row. This pivoting should be the subject of another question.
First, this expression will turn any DATETIME value into the preceding Sunday.
FROM_DAYS(TO_DAYS(value) -MOD(TO_DAYS(value) -1, 7))
Second, here's what you need to select two weeks (last week and this week)
WHERE `DATE` >= FROM_DAYS(TO_DAYS(NOW()) -MOD(TO_DAYS(NOW()) -1, 7)) - INTERVAL 7 DAY
AND `DATE` < FROM_DAYS(TO_DAYS(NOW()) -MOD(TO_DAYS(NOW()) -1, 7)) + INTERVAL 7 DAY
This gets the range of dates starting with the Sunday before last Sunday, and ending the moment before the Sunday after this Sunday, a two week range.
Third, you need to group correctly. In your schema, group by week and by country. It would go something like this:
SELECT SUM(`GP`) AS GP,
`Country`,
FROM_DAYS(TO_DAYS(`DATE`) -MOD(`DATE`) -1, 7)) AS week_beginning
FROM `Finance`
WHERE `DATE` >= FROM_DAYS(TO_DAYS(NOW()) -MOD(TO_DAYS(NOW()) -1, 7)) - INTERVAL 7 DAY
AND `DATE` < FROM_DAYS(TO_DAYS(NOW()) -MOD(TO_DAYS(NOW()) -1, 7)) + INTERVAL 7 DAY
GROUP BY `Country`, FROM_DAYS(TO_DAYS(`DATE`) -MOD(`DATE`) -1, 7))
ORDER BY `Country`, FROM_DAYS(TO_DAYS(`DATE`) -MOD(`DATE`) -1, 7))
This will give you two rows per country, one for the week_beginning a week ago, and one for the current week. This could do the trick for you. If not, you can pivot this query's results to arrange the rows the way you want them. That should be the subject of another question.
Finally, if you can define stored functions in your MySQL instance, you should define the function TRUNC_SUNDAY. Then you can write your query more readably like this:
SELECT SUM(`GP`) AS GP,
`Country`,
TRUNC_SUNDAY(`DATE`) AS week_beginning
FROM `Finance`
WHERE `DATE` >= TRUNC_SUNDAY(NOW()) - INTERVAL 7 DAY
AND `DATE` < TRUNC_SUNDAY(NOW()) + INTERVAL 7 DAY
GROUP BY `Country`, TRUNC_SUNDAY(`DATE`)
ORDER BY `Country`, TRUNC_SUNDAY(`DATE`)
Here is SQL code to define the stored TRUNC_SUNDAY function you need:
DELIMITER $$
DROP FUNCTION IF EXISTS `TRUNC_SUNDAY`$$
CREATE FUNCTION `TRUNC_SUNDAY`(datestamp DATETIME)
RETURNS DATE
NO SQL
DETERMINISTIC
COMMENT 'returns preceding Sunday'
RETURN FROM_DAYS(TO_DAYS(datestamp) -MOD(TO_DAYS(datestamp) -1, 7))$$
DELIMITER ;
You can find a detailed writeup of this technique, including a TRUNC_MONDAY function, here. You'll need the TRUNC_MONDAY function if your weekdays are defined as starting on Monday rather than Sunday. http://www.plumislandmedia.net/mysql/sql-reporting-time-intervals/