Delete comment - actually delete it, or create `deleted` column and update it? I'm really not sure if this is the right community to ask it in, but it seemed like it fits here.

But anyway, I'd like to know what's the usual approach of deleting a comment from database through website?

What I mean: when the user decides to delete his comment for example, does the comment actually get deleted from the database, or do developers create a column like deleted - int(1) default 0, where 0=not deleted, 1=deleted, and that column is being updated from 0 to 1 when a comment is being deleted? In this case, only comments where the deleted column is 0 would be displayed on the site.

Or is there no usual approach for this at all?
I'd say this depends on the set requirements - many projects demand that the database never forgets "things" - to be able to generate reports and so on. In these cases you usually have this deleted column already. On delete you update said column - and for the report-functions you have an additional table that keeps record of who "ordered the delete" (just in case "he" deleted something that wasn't meant to be forgotten).