返回按周分组的行数 MySQL

Question

I am trying to get the row count from a MySQL table where the data is grouped by WEEK.

So far the query I have is:

 "SELECT count(*) as tweets, twitTimeExtracted as date 
  FROM scene.twitData 
  group by week(twitTimeExtracted)"

This query returns the data below:

As you can see, the weeks are not correct, I'm expecting data for each week starting with Monday 7th January (7,14,21,28,4,11 etc...) and running through to this week.

I also tried a modified version of the orignal query:

SELECT count(*) as tweets, twitTimeExtracted as date 
FROM scene.twitData 
WHERE date(twitTimeExtracted) 
   BETWEEN '2013-01-07' and '2013-03-11' 
group by week(twitTimeExtracted)

This returns similar results as the first query.

Maybe there is an inconsistency with some data stored in the DATETIME: twitTimeExtracted column on a few rows of data? I don't really know I'm not very experienced with MySQL.

Any help would really be appreciated.

Thanks

Answer 1

This converts the datetime value to the appropriate Monday of the week

select count(*) as tweets,
       str_to_date(concat(yearweek(twitTimeExtracted), ' monday'), '%X%V %W') as `date`
from twitData 
group by yearweek(twitTimeExtracted)

yearweek returns both week and year. Together with the string monday , str_to_date gives you the Monday's datetime value.

If your week starts on Monday , use yearweek(twitTimeExtracted, 1) instead.

Answer 2

One option to always get the Monday of the week is to use adddate:

SELECT count(*) as tweets, adddate(twitTimeExtracted, INTERVAL 2-DAYOFWEEK(twitTimeExtracted) DAY)
FROM twitData 
WHERE date(twitTimeExtracted) 
   BETWEEN '2013-01-07' and '2013-03-11' 
GROUP BY adddate(twitTimeExtracted, INTERVAL 2-DAYOFWEEK(twitTimeExtracted) DAY)

SQL Fiddle Demo

Answer 3

try this:

 SELECT count(*) as tweets, 
     date_add('7 Jan 2012', day, datediff('7 Jan 2012', twitTimeExtracted)) % 7   
 FROM scene.twitData 
 group by date_add('7 Jan 2012', day, datediff('7 Jan 2012', twitTimeExtracted)) % 7

Answer 4

An alternate solution:

SELECT DATE(DATE_SUB(yourDate, INTERVAL WEEKDAY(yourDate) DAY));

Eg:

SELECT DATE(DATE_SUB(DATE("2016-04-11"), INTERVAL WEEKDAY(DATE("2016-04-11")) DAY));

Answer 5

You can also try this.

select 
DATE_ADD(DATE(date), INTERVAL (7 - DAYOFWEEK(date)) DAY) as weekend,
count(tweets)
from scene.twitData 
  group by weekend;