How to use greater or less than sign in c# mysql update statement : I'm trying to set expiry status of a particular item in the database through my c# winforms application.

So far,
I've tried this
MySqlCommand comm = new MySqlCommand("update items set Expiry = 'Yes' where ExpiryDate > "+ DateTime.Now.ToShortTimeString()+");",connection);
comm.ExecuteNonQuery();

But I'm having issues with it
Thanks