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Retrieving the last record in each group - MySQL
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MySQL 8.0 now supports windowing functions, like almost all popular SQL implementations. With this standard syntax, we can write greatest-n-per-group queries:
WITH ranked_messages AS (
SELECT m.*, ROW_NUMBER() OVER (PARTITION BY name ORDER BY id DESC) AS rn
FROM messages AS m...
Storing Data in MySQL as JSON
.... And, so, I've never done it. Then I saw that FriendFeed did this and actually made their DB scale better and decreased latency. I'm curious if I should do this. And, if so, what's the right way to do it?
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Enabling error display in PHP via htaccess only
... configuration files (e.g. httpd.conf) and .htaccess files. You will need "AllowOverride Options" or "AllowOverride All" privileges to do so. php.net/manual/en/configuration.changes.php
– silex
May 25 '11 at 17:01
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Difference between numeric, float and decimal in SQL Server
...Avoid using float or real columns in WHERE clause search conditions, especially the = and <> operators (Technet)
so generally because the precision provided by decimal is [10E38 ~ 38 digits] if your number can fit in it, and smaller storage space (and maybe speed) of Float is not important a...
Sublime Text 2: Trim trailing white space on demand
...ing spaces and delete them in a flash.
ST2 provides a way to automatically delete trailing spaces upon file
save. Depending on your settings, it may be more handy to just
highlight them and/or delete them by hand. This plugin provides just
that!
Usage: click "Edit / Trailing Spaces / De...
Why do x86-64 instructions on 32-bit registers zero the upper part of the full 64-bit register?
...he CPU would have to wait on. The register renaming mechanism would essentially be defeated if it wasn't done that way.
This way you can write fast code using 32-bit values in 64-bit mode without having to explicitly break dependencies all the time. Without this behaviour, every single 32-bit instr...
What is the difference between an int and an Integer in Java and C#?
...by reference (or more accurately have references passed by value), and are allocated from the heap. Conversely, primitives are immutable types that are passed by value and are often allocated from the stack.
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TFS: Updating branch with changes from main
...e Target branch drop-down, select your dev branch.
If you want a subset of all the changes in the mainline:
Choose the Selected changesets radio button, click Next.
Select the changesets that represent the merge from your other dev's branch into main, click Next.
Otherwise, keep All changes up to ...
What is the meaning of the term arena in relation to memory?
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An arena is just a large, contiguous piece of memory that you allocate once and then use to manage memory manually by handing out parts of that memory. For example:
char * arena = malloc(HUGE_NUMBER);
unsigned int current = 0;
void * my_malloc(size_t n) { current += n; return arena +...
Do c++11 lambdas capture variables they don't use?
When I use [=] to indicate that I would like all local variables to be captured by value in a lambda, will that result in all local variables in the function being copied, or just all local variables that are used by the lambda ?
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