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SQL to determine minimum sequential days of access?
...NUMBER() OVER (PARTITION BY UserID
ORDER BY CreationDate)
- DATEDIFF(day,'19000101',CreationDate) AS TheOffset,
CreationDate,
UserID
FROM tablename)
SELECT MIN(CreationDate),
MAX(CreationDate),
...
Are C# events synchronous?
...y.
The event handlers are executed sequentially, one after another, in the order they are subscribed to the event.
I too was curious about the internal mechanism of event and its related operations. So I wrote a simple program and used ildasm to poke around its implementation.
The short answer i...
How do C++ class members get initialized if I don't do it explicitly?
... mem-initializer-list, and members can only be initialized in a prescribed order (basically the order in which the members are declared in the class). Thus, the members of Example can only be initialized in the order: ptr, name, pname, rname, crname, and age.
When you do not specify a mem-initializ...
List columns with indexes in PostgreSQL
...um = ANY(ix.indkey)
and t.relkind = 'r'
and t.relname like 'test%'
order by
t.relname,
i.relname;
table_name | index_name | column_name
------------+------------+-------------
test | pk_test | a
test | pk_test | b
test2 | uk_test2 | b
test2 | uk_te...
How do cache lines work?
...,5% of its time (if it only reads memory) idle waiting for the memory.
In order to speed things up there is the L1, L2, L3 caches. They use memory being directly placed on the chip and using a different kind of transistor circuits to store the given bits. This takes more room, more energy and is mo...
Easy way to write contents of a Java InputStream to an OutputStream
...this input stream and writes the bytes to the
given output stream in the order that they are read. On return, this
input stream will be at end of stream. This method does not close
either stream.
This method may block indefinitely reading from the
input stream, or writing to the output...
Test if a variable is a list or tuple
...e you can surely pop elements from it, but it does not guarantee a certain order, which is a very dangerous thing for certain algorithms. In the cases when ordering of the elements does matter, an algorithm using this snippet could potentially generate different results on different runs!
...
When to use IMG vs. CSS background-image?
...ze.
Use IMG
for multiple overlay images in IE6.
Use IMG with a z-index in order
to stretch a background image to fill its entire window.Note, this is no longer true with CSS3 background-size; see #6 below.
Using img instead of background-image can dramatically improve performance of animations ove...
Why is quicksort better than mergesort?
...t into a BTREE datastructure for the index. (BTREEs are naturally kept in order, so you can load one from a sorted dataset with few seeks to disk.)
There have been a number of occasions where understanding how to avoid disk seeks has let me make data processing jobs take hours rather than days or ...
Regex - Should hyphens be escaped? [duplicate]
...er in the range (e.g. [-a-z] or [0-9-]), OR escape it (e.g. [a-z\-0-9]) in order to add "hyphen" to your class.
It's more common to find a hyphen placed first or last within a character class, but by no means will you be lynched by hordes of furious neckbeards for choosing to escape it instead.
(A...