tailieunhanh - Joe Celko s SQL for Smarties - Advanced SQL Programming P74

Joe Celko s SQL for Smarties - Advanced SQL Programming P74. In the SQL database community, Joe Celko is a well-known columnist and purveyor of valuable insights. In Joe Celko's SQL for Smarties: Advanced SQL Programming, he picks up where basic SQL training and experience leaves many database professionals and offers tips, techniques, and explanations that help readers extend their capabilities to top-tier SQL programming. Although Celko denies that the book is about database theory, he nevertheless alludes to theory often to buttress his practical points. This title is not for novices, as the author points out. Instead, its intended. | 702 CHAPTER 30 GRAPHS IN SQL arrival_town steps total_distance TOULOUSE 3 1015 TOULOUSE 2 795 TOULOUSE 3 995 The girl hiding in the cake is the ability to determine which different towns we visit by using each of these different routes WITH RECURSIVE Journeys arrival_town steps total_distance way AS SELECT DISTINCT depart_town 0 0 CAST PARIS AS VARCHAR MAX FROM Journeys WHERE depart_town PARIS UNION ALL SELECT arrival_town 1 FROM Journeys AS Arrivals Journeys AS Departures WHERE SELECT arrival_town steps total_distance way FROM Journeys WHERE arrival_town TOULOUSE arrival_town steps total_distance way TOULOUSE 3 1015 PARIS LYON MONTPELLIER TOULOUSE TOULOUSE 2 795 PARIS CLERMONT-FERRAND TOULOUSE TOULOUSE 3 995 PARIS CLERMONT-FERRAND MONTPELLIER TOULOUSE And now ladies and gentleman the recursive query is proud to present to you the means of solving a very complex problem called the traveling salesman problem. This is one of the operational research problems for which Edsger Wybe Dijkstra found the first efficient algorithm and received the Turing Award in 1972. WITH RECURSIVE Journey arrival_town steps total_distance way AS SELECT DISTINCT depart_town 0 0 CAST PARIS AS VARCHAR MAX FROM Journeys WHERE depart_town PARIS Paths with CTE 703 UNION ALL SELECT arrival_town 1 FROM Journeys AS Arrivals Journeys AS Departures WHERE ShortestDistance total_distance AS SELECT MIN total_distance FROM Journeys WHERE arrival_town TOULOUSE SELECT arrival_town steps total_distance way FROM Journeys AS J ShortestDistance AS S WHERE AND arrival_town TOULOUSE Nonacyclic Graphs In fact one thing that is limiting the process in our network of speedways is

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