I comment on forums as part of my daily routine. I’ve worked through different problem sets and find helping other people keeps my problem solving and research skills sharp.
I’ve observed a trend amongst forums with developers and DBAs attempting to learn query tuning over a forum without possessing the basic knowledge of SQL Server internals such as query processing , indexes and execution plans.
There are many forum posts asking for assistance in tuning a query and requests to teach query tuning. Query Tuning cannot be taught over forums. Invest some time in reading some books , working through the problems offered in the books. There are some great books available teaching internals and offering deep insights into SQL Server. Once you grasp the basics query tuning becomes significantly easier.