Splitting month into weeks and using GROUP BY - php

Question

This is a question, which I could not find answer to anywhere. Okay. here it is.
I have two date ranges (This month and the last month)
Last month - 01/01/2015 (January 1 2015) to 31/01/2015
This month - 01/02/2015 (1st Feb 2015) to 28/02/2015
Now, each month has weeks. I have a table with column created_at. I want to fetch all the records week-wise into an array (to plot a graph) with their corresponding sum(value) or count(value) .
So it will be something like this:
Last Month:
Week 1 - 25
Week 2 - 34
etc.
This Month:
Week 1: 55
Week 2: 56
etc.
The date is in this format in created_at: 2015-07-21 01:27:14 (Y-m-d H:i:s)

Answer 1

In MySql You can use WEEK() to get the number of the week (from 1 to 53)
O you can use WEEKDAY() or DAYOFWEEK() the first bigins on Monday the second on Sunday.
You can use them into a GROUP BY with HAVING
Something like:
SELECT count(*)
FROM `YourTable`
WHERE `created_at` >= '2015-10-01' AND `created_at`< '2015-11-01'
GROUP BY WEEK(`created_at`)
To use the workaround you found You need to do something similar:
create a table named "numbers" with a field "id" (autoincrement) and 31 rows (one for each day of a month)
Then use a query like this:
SELECT count(i.created_at)
FROM
(SELECT DATE_FORMAT(DATE_ADD('2015-12-01', INTERVAL -n.id DAY), '%Y-%m-%d') AS AllDays
FROM numbers n) AS DaysOfMonth
Left Join
YourTableName i
ON STR_TO_DATE(i.created_at, '%Y-%m-%d') = DaysOfMonth.AllDays
GROUP BY WEEK(AllDays)
(try to adapt it to your needs)

Answer 2

What you need to do is group by the week and then sum the values. Here's a simple example of how it might work:
SELECT DATE_FORMAT(created_at,'%Y-%V') as interval, SUM(units_sold) as total_sold
FROM sales
GROUP BY DATE_FORMAT(created_at,'%Y-%V')
What you'll be getting is the year ant week number (ex. 2015-50) and the sum from that interval.
A table like this:
+----+------------+---------------------+
| id | units_sold | created_at |
+----+------------+---------------------+
| 1 | 2 | 2015-01-01 09:00:00 |
| 2 | 4 | 2015-01-04 10:00:00 |
| 3 | 1 | 2015-01-12 12:00:00 |
| 4 | 4 | 2015-01-16 13:00:00 |
+----+------------+---------------------+
Would result to:
+----------+------------+
| interval | total_sold |
+----------+------------+
| 2015-01 | 6 |
| 2015-03 | 5 |
+----------+------------+

Answer 3

I think it is useful for you...
SELECT GROUP_CONCAT(id), COUNT(id) AS idcount,SUM(id) AS idsum,
MONTHNAME(order_created_date) AS month_name, WEEK(order_created_date)
AS weeks FROM orders GROUP BY WEEK(order_created_date)