Selecting data interval

Question

I have a table that has date and id column. How can I select id's of 7 days interval?

My data is:

date            id 
2013-07-01      11
2013-07-02      22
2013-07-03      33
2013-07-04      33
2013-07-05      44  
2013-07-06      44      
2013-07-07      45  
2013-07-08      46  
2013-07-09      47
2013-07-10      48
2013-07-11      48
2013-07-12      49
2013-07-13      50
2013-07-14      51
2013-07-15      52
2013-07-16      52
2013-07-17      53
2013-07-18      53
2013-07-19      54

What I want is:

date            id
2013-07-01      11
2013-07-08      46
2013-07-15      52

Thanks

Answer 1

SELECT date,id FROM table1 GROUP BY WEEK(`date`, 1)

http://sqlfiddle.com/#!2/b128c/1