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Why do Objective-C files use the .m extension?
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What is the most efficient way to store a list in the Django models?
...ng data is very common. Done correctly, it can save numerous expensive database lookups at the cost of a little more housekeeping.
To return a list of friend names we'll need to create a custom Django Field class that will return a list when accessed.
David Cramer posted a guide to creating a Sepe...
MySQL: Selecting multiple fields into multiple variables in a stored procedure
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How to track child process using strace?
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Nginx location priority
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Can you help me understand Moq Callback?
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What is routes.IgnoreRoute(“{resource}.axd/{*pathInfo}”)
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JavaScript for…in vs for
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The choice should be based on the which idiom is best understood.
An array is iterated using:
for (var i = 0; i < a.length; i++)
//do stuff with a[i]
An object being used as an associative array is iterated using:
for (var key in o)
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How do I get the MIN() of two fields in Postgres?
...ST are not in the SQL standard, but are a common extension. Some other databases make them return NULL if any argument is NULL, rather than only when all are NULL...
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PostgreSQL DISTINCT ON with different ORDER BY
...sed_at
ORDER BY t1.purchased_at DESC
A more PostgreSQL-oriented solution based on @hkf's answer:
SELECT * FROM (
SELECT DISTINCT ON (address_id) *
FROM purchases
WHERE product_id = 1
ORDER BY address_id, purchased_at DESC
) t
ORDER BY purchased_at DESC
Problem clarified, extended and s...