Help?

Don't know if you guys help round here but ill give it a go.

This is SQL

query = "UPDATE event_info"
        + "SET PLACES = PLACES   -1 "
        + "WHERE EID = '"+intID+"' ";
stmt.execute(query);

Whats wrong here? its a booking system When i book i want available places to go down by 1, Places is an int EID is also an int