I personally think any black-or-white approach to substances or behaviours that may be harmful in excess is not the best way to choose.
I will on purpose ignore legal aspects for most of this answer (but see the bottom for that topic).
We as parents are responsible to teach our children moderation and how to deal with temptation. We know that too much refined sugar is "bad"1 for us. Yet many children have sweet cereal, soft drinks and the occasional candy bar. And together with a balanced diet and exercise, this is no problem. But too much of it certainly is.
On the other hand, we all have seen children from very strict households, where sweet stuff is forbidden, "pounce" on cake and candy at parties or invest their pocket money in chocolate bars which they often consume in secret, hiding from their parents.
Now feel free to substitute sugar with coffee, alcohol, sex... for older teens and young adults and you'll probably see a pattern.
If we look at the question from a more general angle, teaching our children to deal with all sorts of temptation, is a way of setting them up for success. Let me remind you of the famous Marshmallow Test: Children are placed in front of something they like (a marshmallow) and promised a second one if they managed to not eat the one in front of them while the person administering the test leaves the room. Children that could control their impulse in the test were found to be statistically more likely to do well later in life - better grades, but also a lower risk of substance abuse. Newer research suggests that this impulse control and ability to deal with delayed gratification can be trained.
(And it's probably a good thing to do so.)
But how are we going to teach healthy behavioural patterns? Like everything else: we model and explain. And this is true for all aspects of life. Food, TV habits, relationships, and, yes, alcohol and cigarettes. Reminder: Children have fine antennae for hypocrisy. They observe what's going on both in your household and in the rest of the society we live in.
So be prepared to have your behaviour questioned, but even if you don't drink, the adult society as a whole does, at least occasionally.
For younger children, it is easy to divide between "what adults can do" and "what children can do" - the examples are manigfold: driving a car, voting in a election, ...and drinking coffee, beer or wine.
When children get older, we gradually give them liberties and responsibilities. We also broach "sensitive" topics like responsible sex. (And that is way different once your teen has a girlfriend or boyfriend and you leave the safe world of theoretical explanations.)
Teaching how to deal responsibly with alcohol falls into the same category (but without the "ewwww" factor). So if you have an occasional glass of wine, I suggest you don't worry, but model how an adult drinks responsibly: not habitually and in moderation. In our society, alcohol consumption is part of social gatherings - a great way of showing your teen how having a designated driver works. Talk and explain. Explain, how alcohol lowers self-control. Explain strategies how to deal with peer pressure or how and when to switch to non-alcoholic beverages during a party. And - that's my personal opinion - if an older teen can experience the first effects of alcohol in the safe surroundings of home, they know the signs and when to stop drinking.
And you de-mystify the stuff: for my (younger) children, coffee and alcoholic beverages are "yuck" - they know that they may ask to taste whatever we are having, but have decided for themselves, that they are not interested.
Now to the legal aspects:
Countries have different laws. Your child must know and obey the laws - like everyone else. You might want to double-check, though: While your older teen might not be able to buy and drink alcohol in a shop or restaurant, it may be perfectly legal for your child to try a sip of beer or wine at home and under your supervision as a parent.
But above all, make totally clear that you as parent will always be there to pick your child up if a designated driver has been drinking or your child ignored the law and feels tipsy. The life and safety of your child may depend on that.
1 obviously simplified, but I didn't want to list effects here