How to Misuse SQL's FROM Clause

"It may seem surprising to state it so, but the FROM clause of SQL statements seems to be one of the most often misused parts of SQL queries. Misused? How is that possible? We put into the FROM clause all the tables to join together in a query, don't we? Well, well, well. Not quite. At the risk of sounding pedantic, perhaps a bit of (applied) theory would be welcome."
Story

 (Submitted by Noel Fri Oct 1, 2004 )