> “Find all flights from Detroit to Beijing” ... which must be joined twice with flight info to express our query Actually this can be done by nested query, wi

> “Find all flights from Detroit to Beijing” ... which must be joined twice with flight info to express our query Actually this can be done by nested query, without joining. I prefer nested query than joins. Because join is "global" and nested query is "local" (global means interfering with the whole SQL statement). The local one is easier to understand.