Although I've been doing lots of work with SQL over the years, I've never done anything with stored procedures. While reading a book on MySQL stored programs, I'm struck by the fact that the common method of iterating through a resultset using a cursor requires doing "exception-based branching" (a NOT FOUND handler). Typically, in conventional programming languages, doing exception-based branching is considered very bad practice. It seems, however, that the tools available in a PSM limits you to this strategy, in the common cases.
It occurred to me, however, that another way to do this would be to "UNION" in a hardcoded row of at least one "impossible" hardcoded value (sometimes called a sentinel) that is used for checking for the last row (or in this case, one past the last row of real data). This would allow for detecting the end of the resultset without using exception-based branching. The important question is, is it even worth it? Is exception handling in a MySQL PSM more expensive than normal processing, like it's considered to be in other languages, like Java? If this works, would it make the resulting code harder to understand than the conventional strategy? Is this a deranged idea?
