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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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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...
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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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...
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...
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...
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...
Filling a DataSet or DataTable from a LINQ query result set
...has a CopyToDataTable method:
IEnumerable<DataRow> query =
from order in orders.AsEnumerable()
where order.Field<DateTime>("OrderDate") > new DateTime(2001, 8, 1)
select order;
// Create a table from the query.
DataTable boundTable = query.CopyToDataTable<DataRow>(...
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...