I have a large list of sales info that tabulates who bought which books. The book titles are listed as headers, with a "1" in the corresponding row to show which email purchased which book. I'd like to take the book titles and combine into one cell, separated by commas, like so: book1, book2, book3. This way, there will be one column summarizing all the books someone bought in one cell.

Here is small table to represent what I'm trying to do. Please keep in mind that I have over 30 columns and 16,000 rows so a simple IF and Concatenate function will not work. I'd like to have the values appear in the Book Summary column.

Thanks for all your help!

What I have currently:
Name Book Summary Book Title 1 Book Title 2 Book Title 3
[email protected] 1 1
[email protected] 1
[email protected] 1 1


What I Seek:
Name Book Summary Book Title 1 Book Title 2 Book Title 3
[email protected] book1, book2 1 1
[email protected] book2 1
[email protected] book2, book3 1 1