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What is the purpose of setting a key in data.table?
I am using data.table and there are many functions which require me to set a key (e.g. X[Y] ). As such, I wish to understand what a key does in order to properly set keys in my data tables.
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Which is more efficient: Multiple MySQL tables or one large table?
...inally it was set up in various tables meaning data is linked with UserIds and outputting via sometimes complicated calls to display and manipulate the data as required. Setting up a new system, it almost makes sense to combine all of these tables into one big table of related content.
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How can I run dos2unix on an entire directory? [closed]
...args -0 dos2unix
Will recursively find all files inside current directory and call for these files dos2unix command
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Detailed 500 error message, ASP + IIS 7.5
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I have come to the same problem and fixed the same way as Alex K.
So if "Send Errors To Browser" is not working set also this:
Error Pages -> 500 -> Edit Feature Settings -> "Detailed Errors"
Also note that if the content of the error page sen...
Why is enum class preferred over plain enum?
...ce between the two?
enum classes - enumerator names are local to the enum and their values do not implicitly convert to other types (like another enum or int)
Plain enums - where enumerator names are in the same scope as the enum and their
values implicitly convert to integers and other types
Ex...
How to connect to SQL Server database from JavaScript in the browser?
..., among others. Client javascript should be used only for the interfaces.
And there are rumors of an ancient legend about the existence of server javascript, but this is another story. ;)
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How to drop a PostgreSQL database if there are active connections to it?
...s will drop existing connections except for yours:
Query pg_stat_activity and get the pid values you want to kill, then issue SELECT pg_terminate_backend(pid int) to them.
PostgreSQL 9.2 and above:
SELECT pg_terminate_backend(pg_stat_activity.pid)
FROM pg_stat_activity
WHERE pg_stat_activity.datn...
visual studio not remembering open documents & startup project
For the past week, something has changed about my VS solution, and I havent found a setting to fix it yet.
16 Answers
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How to use enums in C++
...== Days.Saturday)
Because Days is not a scope, nor object. It is a type. And Types themselves don't have members. What you wrote is the equivalent to std::string.clear. std::string is a type, so you can't use . on it. You use . on an instance of a class.
Unfortunately, enums are magical and so ...
Multiple GitHub Accounts & SSH Config
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Andy Lester's response is accurate but I found an important extra step I needed to make to get this to work. In trying to get two profiles set up, one for personal and one for work, my ~/.ssh/config was roughly as follows:
H...