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What is the most efficient/elegant way to parse a flat table into a tree?
..., we can say that all popular SQL databases support recursive queries in standard syntax.
WITH RECURSIVE MyTree AS (
SELECT * FROM MyTable WHERE ParentId IS NULL
UNION ALL
SELECT m.* FROM MyTABLE AS m JOIN MyTree AS t ON m.ParentId = t.Id
)
SELECT * FROM MyTree;
I tested recursive que...
Best practices for SQL varchar column length [closed]
...t into it, not the max length you define. So from a storage point of view (and most probably a performance one as well), it does not make any difference whether you declare a column as VARCHAR(100) or VARCHAR(500).
You should see the max length provided for a VARCHAR column as a kind of constraint...
Difference between git checkout --track origin/branch and git checkout -b branch origin/branch
Does anybody know the difference between these two commands to switch and track a remote branch?
4 Answers
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How can I use functional programming in the real world? [closed]
...at will pass functions off to different CPU's or machines. What F#/Haskell and other functional programming languages do is make it easier for you to write functions that can be processed independent of the thread or CPU they were created on.
I don't feel right posting a link here to a podcast I pa...
How to center a “position: absolute” element
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Smartest answer. I have just checked it and it works on all browsers. It does not work on IE8 but it works on IE>=9
– Roger
Dec 11 '13 at 9:43
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How to properly add include directories with CMake
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This way, the header files will appear as dependencies in the Makefile, and also for example in the generated Visual Studio project, if you generate one.
How to use those header files for several targets:
set(HEADER_FILES ${YOUR_DIRECTORY}/file1.h ${YOUR_DIRECTORY}/file2.h)
add_library(mylib l...
WPF Data Binding and Validation Rules Best Practices
...plex.com), which includes a demo of best practices validation in WPF+MVVM, and uses IDataErrorInfo
– Mark Heath
Sep 4 '09 at 6:37
3
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What's the difference between SoftReference and WeakReference in Java?
What's the difference between java.lang.ref.WeakReference and java.lang.ref.SoftReference ?
12 Answers
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C# Passing Function as Argument [duplicate]
...s mentioned above works but there are also delegates that do the same task and also define intent within the naming:
public delegate double MyFunction(double x);
public double Diff(double x, MyFunction f)
{
double h = 0.0000001;
return (f(x + h) - f(x)) / h;
}
public double MyFunctionMet...
git: Switch branch and ignore any changes without committing
I was working on a git branch and was ready to commit my changes, so I made a commit with a useful commit message. I then absentmindedly made minor changes to the code that are not worth keeping. I now want to change branches, but git gives me,
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