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Retrieving the last record in each group - MySQL
...
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...
SignalR: Why choose Hub vs. Persistent Connection?
...persistent connections.
From the highly up-voted comment below:
Partially correct. You can get topics or groups in persistent connections as well. The big difference is dispatching different types of messages. For example you have different kinds of messages and you want to send different kind...
CSS - Overflow: Scroll; - Always show vertical scroll bar?
... 4em and scroll to show the rest */
}
#child {
height: 12em;
/* taller than the parent to force scrolling */
}
/* === ignore stuff below, it's just to help with the visual. === */
#container {
background-color: #ffc;
}
#child {
margin: 30px;
background-color: #eee;
...
Securing my REST API with OAuth while still allowing authentication via third party OAuth providers
...web site by supplying some credential such as a username+password. OpenID allows this to be displaced by having the user authenticate to another service, which then asserts the user's identity to your web site on the user's behalf. Your site trusts the third party service (the OpenID Provider) and...
Why do Java webapps use .do extension? Where did it come from?
...oach will be described
below.
Prefix matching means that you want
all URLs that start (after the context
path part) with a particular value to
be passed to this servlet. Such an
entry might look like this:
<servlet-mapping>
<servlet-name>action</servlet-name>
...
SSO with CAS or OAuth?
...and in implementation.
CAS centralizes authentication. Use it if you want all your (probably internal) applications to ask users to login to a single server (all applications are configured to point to a single CAS server).
OpenID decentralizes authentication. Use it if you want your application t...
What do these words mean in Git: Repository, fork, branch, clone, track?
I'm honestly not clear on the semantics here. They're all about copies/variants of a code+history unit, but past that I'm not sure I could say. Is this logical structure explained somewhere?
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Can you write virtual functions / methods in Java?
...
From wikipedia
In Java, all non-static methods are by
default "virtual functions." Only
methods marked with the keyword final,
which cannot be overridden, along with
private methods, which are not
inherited, are non-virtual.
...
Undo a git stash
...ll not reset what is in the staging directory, so you will have to restage all that (which can be annoying if you had just done a complex git add -p
– Nick
Jan 2 '13 at 17:31
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Why does Clojure have “keywords” in addition to “symbols”?
...vide very fast equality tests...
Symbols are identifiers that are normally used to refer to something else. They can be used in program forms to refer to function parameters, let bindings, class names and global vars...
Keywords are generally used as lightweight "constant strings", e.g. for t...