That is the best bit of MySQL information re indexes. I have not found that anywhere else. I have some re-coding to do as I have used some 'likes' in my statements.
I have not used the 'explain' statement. I'll read up on that.
Most often, my users have to search the main database tables by a number of fields simultanuously, ie, ToDate, FromDate, Name, OrderType, etc, to generate the report they need to see. If I created an index to cover all fields that can appear in a requested search, I would end up indexing virtually every field. What rules of thumb are their to help me decide what to index? Sorry if this is such a noobie question, but I have never managed to get my head around this.