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Counting DISTINCT over multiple columns
... you are trying to improve performance, you could try creating a persisted computed column on either a hash or concatenated value of the two columns.
Once it is persisted, provided the column is deterministic and you are using "sane" database settings, it can be indexed and / or statistics can be ...
How to return smart pointers (shared_ptr), by reference or by value?
... a increment-increment-decrement sequence or something like that in modern compilers. So the best way to return a shared_ptr is to simply return by value:
shared_ptr<T> Foo()
{
return shared_ptr<T>(/* acquire something */);
};
This is a dead-obvious RVO opportunity for modern C++ ...
What's the difference between hard and soft floating point numbers?
When I compile C code with my cross toolchain, the linker prints pages of warnings saying that my executable uses hard floats but my libc uses soft floats. What's the difference?
...
Submit form using a button outside the tag
...ontrol.
http://www.w3.org/TR/html4/interact/forms.html#h-17.2.1
From the comments
I have a multi tabbed settings area with a button to update all, due
to the design of it the button would be outside of the form.
Why not place the input inside the form, but use CSS to position it elsewhere ...
AI助手重构版问题记录 - AI 助手 - 清泛IT社区，为创新赋能！
... "https://api.weatherapi.com/v1/current.json?key=demo&q=",
{
"get_...
When should I use GC.SuppressFinalize()?
...g the Garbage Collector (GC) that this object was cleaned up fully.
The recommended IDisposable pattern when you have a finalizer is:
public class MyClass : IDisposable
{
private bool disposed = false;
protected virtual void Dispose(bool disposing)
{
if (!disposed)
{
...
What is the difference between “Rollback…” and “Back Out Submitted Changelist #####” in Perforce P4V
...tially faster, safer ways of undoing mistakes than using the p4 obliterate command (and you don't need admin access to use them).
In the case of "Rollback...", this could be any number of files, even an entire depot. You can tell it to rollback to a specific revision, changelist, or label. The ...
Script parameters in Bash
...iables $1 and $2 and $3 where the number refers to the argument. $0 is the command itself.
The arguments are seperated by spaces, so if you would provide the -from and -to in the command, they will end up in these variables too, so for this:
./ocrscript.sh -from /home/kristoffer/test.png -to /home...
How do I change bash history completion to complete what's already on the line?
I found a command a couple of months ago that made my bash history auto-complete on what's already on the line when pressing the up arrow:
...
Why does X[Y] join of data.tables not allow a full outer join, or a left join?
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