In the iPhone's messages list, where does the date come from?

This is maybe a weird question. In the iPhone's "Messages" app, the first view is a list of all the chats, sorted by the most recent messages in each chat. To the right of each chat entry is a date (circled in my screenshot) which is the essence of my question. This date seems to be the date of the *last* message received in the chat, even when that message has been subsequently deleted from the chat. Ultimately I was playing around in the sqlite database to see how the messages were represented in there and I can't figure this out. The chat list seems to be sorted by the most recent *current* messages in each chat, but that timestamp shown can be the timestamp of a deleted message, which seems weird. So, why does the messages app show a timestamp for a message that doesn't exist anymore, and where in the sqlite message database does that timestamp live?