This month, I want to introduce a problem that I like to think of as identifying sections. The generic form of the problem involves a table (call it T1) that has two columns of interest: one representing order among rows (call it id) and the other holding some value (call it val). The task at hand is to identify sections of consecutive rows that share the same value. The terms section and consecutive rows are problematic when you're dealing with sets, but as I mentioned, the co...