Instead of
Table Main
ID | name | image | day1 | day2 | day3 ...
-------------------------------------------
1 | Foo | img1 | 7 | NULL | NULL
2 | Bar | img2 | 9 | 13 | 14
You should normalize your data into two tables like this:
Table Main
ID | name | image
------------------
1 | Foo | img1
2 | Bar | img2
Table Days
ID | MainID | Day
------------------
100 | 1 | 7
101 | 2 | 9
102 | 2 | 13
103 | 2 | 14
Then, you will use a JOIN to select all of the days that apply to whichever element from the Main table you're interested in.
An additional benefit here is that you're no longer constrained to just 10 days.