How to find missing rows (dates) in a mysql table?

Question

I have tried several topics like this one: How to find missing data rows using SQL? here, but I couldn\'t make it work in my situation.

I have a table named po

Answer 1

You could automatically enter an empty post each time (end of day) with null titles, null contents but actual date. Then, if the user wants to add a post for a previous day, display all the posts with null titles and contents and update the one he selects.

This shouldn't be a space problem, not if they write more than they miss. For instance, if they write for 4 days and miss 1.

Also, you would run a script and delete entries with null titles, null contents AND date older than X days. If they haven't added the missing post for X days, they probably will never do.

I apologize if my solution is trivial / too abstract.