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What is the most efficient/elegant way to parse a flat table into a tree?
...ation Recursive Query Throwdown in 2017.
Below is my original answer from 2008:
There are several ways to store tree-structured data in a relational database. What you show in your example uses two methods:
Adjacency List (the "parent" column) and
Path Enumeration (the dotted-numbers in yo...
Measure time in Linux - time vs clock vs getrusage vs clock_gettime vs gettimeofday vs timespec_get?
...ecause "the resolution of the system clock is hardware dependent". POSIX.1-2008 says that. "Applications should use the clock_gettime() function instead of the obsolescent gettimeofday() function", so you should stay away from it. Linux x86 and implements it as a system call.
mach_absolute_time() is...
DateTime vs DateTimeOffset
... was created/updated). As a side note, we use DATETIMEOFFSET in SQL Server 2008 as well.
I see DateTime as being useful when you want to deal with dates only, times only, or deal with either in a generic sense. For example, if you have an alarm that you want to go off every day at 7 am, you could s...
When would anyone use a union? Is it a remnant from the C-only days?
...As the authors of a recommendation for the ISO C++ Standard put it back in 2008,
Many important problem domains require either large numbers of objects or limited memory
resources. In these situations conserving space is very important, and a union is often a perfect way to do that. In fact, a...
How to handle dependency injection in a WPF/MVVM application
...compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DataContext="{d:DesignInstance Type=local:MyViewModel, IsDesignTimeCreatable=True}"
The view-model type should have two constructors, the default for design-time data and another for dependency inje...
内存管理内幕：动态分配的选择、折衷和实现 - C/C++ - 清泛网 - 专注C/C++及内核技术
...都获得了自己可以使用的地址空间，可以访问比您物理上安装的内存更多的内存。
在 32-位 x86 系统上，每一个进程可以访问 4 GB 内存。现在，大部分人的系统上并没有 4 GB 内存， 即使您将 swap 也算上， 每个进程所使用的内存...
What does 'COLLATE SQL_Latin1_General_CP1_CI_AS' do?
... (for SQL Server 2005, which is version 9.0), most are 100 (for SQL Server 2008, version 10.0), and a small set has 140 (for SQL Server 2017, version 14.0).
I said "for the most part" because the collations ending in _SC were introduced in SQL Server 2012 (version 11.0), but the underlying data was...
Filter rows which contain a certain string
...tat-computing.org/dataexpo/2009/the-data.html
df <- read_csv("Downloads/2008.csv")
print(dim(df))
# [1] 7009728 29
benchmark(
"str_detect" = {df %>% filter(str_detect(Dest, 'MCO|BWI'))},
"grepl" = {df %>% filter(grepl('MCO|BWI', Dest))},
replications = 10,
columns = c("test", ...
What is the real overhead of try/catch in C#?
...for "exceptional behaviour" or conditions: blogs.msdn.com/kcwalina/archive/2008/07/17/…
– HTTP 410
Oct 24 '08 at 16:56
2
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Real life example, when to use OUTER / CROSS APPLY in SQL
...oo2 INT, Foo3 INT,
Bar1 INT, Bar2 INT, Bar3 INT
);
Example using 2008+ VALUES syntax.
SELECT Id,
Foo,
Bar
FROM T
CROSS APPLY (VALUES(Foo1, Bar1),
(Foo2, Bar2),
(Foo3, Bar3)) V(Foo, Bar);
In 2005 UNION ALL can be...