> in the sense that it makes you specify the joins. Over and over and over again. Why doesn't it infer them from the structure of the database (the relations be

> in the sense that it makes you specify the joins. Over and over and over again. Why doesn't it infer them from the structure of the database (the relations between tables)? The answer is that there are different kind of joins (you may object that this is part of "set of constraints on the desired rows", however, then you are just specifying joins explicitly), and that generally speaking this is a non-unique property, i.e. you could usually infer several joins that represent dramatically different result sets that still have the same tuple archetype. I should point out that these issues aren't brought on by the added expressiveness of SQL, but rather, these issues are already present in basic relational algebra; I'd argue they're fairly fundamental.