Calendar Event Tags

Alright /prog/ - Working on a site for a client. Currently we have an event system up so that the owner (and eventually customers) can easily add events to the calendar for customers to see online. It is set up pretty simply with each event being an entry in a MySQL table currently set up like this:

id
filename (for images)
date
time
timeEnd
eventName
description
host
hostID
ip


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That said, I was talking to the owner last night and she would like it so she could add tags to the events so that when people look at the calendar, they can filter it to see only relevant content.

Honestly, I don't see the reason for it as I doubt there are ever going to be that many simultaneous events. That said, I don't think I'm going to be able to convince her otherwise.

Right now I'm considering using a second table for each tag and linking it to the event ID. Then simply grab all the event ID's with a given tag when rendering the calendar. Any other thoughts on how I should implement this best? (I've never worked with creating a tagging system before)

Tagging is an archetypical many-to-many relationship (there are subtleties if you care about performance, but you don't.) Representing this in a relational database is a well-understood problem.
Why do people try to design databases without any sort of formal training whatsoever, as if it was some sort of menial work? Is reading an introductory book too hard?