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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...
How are 3D games so efficient? [closed]
... a completely full-featured hardware device which is unlikely to exist, in order to show off all the features of the API. But since the hardware doesn't actually exist, it runs on your CPU instead. That's much more inefficient than delegating to a graphics card -- hence your high CPU usage.
...
MySQL Error 1153 - Got a packet bigger than 'max_allowed_packet' bytes
...
On CentOS 5, my.cnf is located at /etc/my.cnf
– Rustavore
May 28 '14 at 23:53
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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...
How does the Java 'for each' loop work?
...or the same thing. Therefore, when reading each element, one by one and in order, a foreach should always be chosen over an iterator, as it is more convenient and concise.
foreach
for(int i : intList) {
System.out.println("An element in the list: " + i);
}
Iterator
Iterator<Integer> in...
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...
Using mixins vs components for code reuse in Facebook React
...ycle methods (componentDidMount etc). This problem is solved by the Higher-Order Components that Dan Abramov talk in his link (or by using ES6 class inheritance).
Mixins are also often used in frameworks, to make framework API available to all the components, by using the "hidden" context feature o...
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...