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SQL join: selecting the last records in a one-to-many relationship
... customer c INNER JOIN
(SELECT RANK() OVER (PARTITION BY customer_id ORDER BY date DESC) r, *
FROM purchase) p
ON (c.id = p.customer_id)
WHERE p.r = 1
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Sort a single String in Java
...a lot harder... hopefully you don't need this :) In addition, this is just ordering by ordinal, without taking capitalisation, accents or anything else into account.
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Are static variables shared between threads?
...ppens-before every action in that thread that comes later in the program's order.
An unlock (synchronized block or method exit) of a monitor happens-before every subsequent lock (synchronized block or method entry) of that same monitor. And because the happens-before relation is transitive, all act...
Is it possible to Pivot data using LINQ?
...lect(g => new {
CustId = g.Key,
Jan = g.Where(c => c.OrderDate.Month == 1).Sum(c => c.Qty),
Feb = g.Where(c => c.OrderDate.Month == 2).Sum(c => c.Qty),
March = g.Where(c => c.OrderDate.Month == 3).Sum(c => c.Qty)
});
GroupBy in Linq does not...
Unable to understand useCapture parameter in addEventListener
...g ("capture"), and at the end ("bubble").
Events are executed in the order of how they're defined. Say, you define 4 event listeners:
window.addEventListener("click", function(){console.log(1)}, false);
window.addEventListener("click", function(){console.log(2)}, true);
window.addEventL...
Rails has_and_belongs_to_many migration
...le with only a restaurant_id and user_id (no primary key), in alphabetical order.
First run your migrations, then edit the generated migration file.
Rails 3
rails g migration create_restaurants_users_table
Rails 4:
rails g migration create_restaurants_users
Rails 5
rails g migration Create...
JavaScript function order: why does it matter?
...functions are called until the whole thing has downloaded. So why does the order functions appear in my code matter?
4 Answ...
How to rollback a specific migration?
...e error in the original post)
rake db:migrate VERSION=20100905201547
In order to rollback ONLY ONE specific migration (OUT OF ORDER) use:
rake db:migrate:down VERSION=20100905201547
Note that this will NOT rollback any interceding migrations -- only the one listed. If that is not what you inte...
Why use ICollection and not IEnumerable or List on many-many/one-many relationships?
...operties in Entity Framework come with change tracking and are proxies. In order for the dynamic proxy to be created as a navigation property, the virtual type must implement ICollection.
A navigation property that represents the "many" end of a relationship must return a type that implements IC...
How do I prevent site scraping? [closed]
... to GitHub to read the extended version, with more tips and details.
In order to hinder scraping (also known as Webscraping, Screenscraping, Web data mining, Web harvesting, or Web data extraction), it helps to know how these scrapers work, and
, by extension, what prevents them from working wel...