大约有 16,000 项符合查询结果（耗时：0.0201秒） [XML]
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...ame as its table name:
CREATE TABLE fruit -- ORM-friendly name
(
fruit_id int NOT NULL,
fruit varchar(50), /* same name as table name,
and let's say, someone forgot to put NOT NULL */
shape varchar(50) NOT NULL,
color varchar(50) NOT NULL
)
Counting with null
And also, it is not...
Task vs Thread differences [duplicate]
... @LeonidVasilyev: Not directly Task related (this was before Tasks were introduced), but I did starve the thread pool once doing some image analysis work. I was using (too many really) the thread pool for object detection, but was pushing the results using an SDK which also used the threadpool. T...
Benefits of EBS vs. instance-store (and vice-versa) [closed]
...tched from S3.
If the hardware your EBS-backed instance is scheduled for maintenance, stopping and starting the instance automatically migrates to new hardware. I was also able to move an EBS-backed instance on failed hardware by force-stopping the instance and launching it again (your mileage may v...
Find the Smallest Integer Not in a List
An interesting interview question that a colleague of mine uses:
28 Answers
28
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Null vs. False vs. 0 in PHP
...xt". Used to explicitly show you are dealing with logical issues.
0 is an int. Nothing to do with the rest above, used for mathematics.
Now, what is tricky, it's that in dynamic languages like PHP, all of them have a value in a boolean context, which (in PHP) is False.
If you test it with ==, it'...
Python: fastest way to create a list of n lists
...epeat
d = [[] for i in repeat(None, n)]
It does not have to create a new int object in every iteration and is about 15 % faster on my machine.
Edit: Using NumPy, you can avoid the Python loop using
d = numpy.empty((n, 0)).tolist()
but this is actually 2.5 times slower than the list comprehensi...
When should I use std::thread::detach?
...) the the destructor of an enclosing class?
– Jose Quinteiro
Nov 23 '16 at 17:59
4
@JoseQuinteiro...
Is the order of iterating through std::map known (and guaranteed by the standard)?
...p 's elements are sorted according to the keys. So, let's say the keys are integers. If I iterate from std::map::begin() to std::map::end() using a for , does the standard guarantee that I'll iterate consequently through the elements with keys, sorted in ascending order?
...
Insert/Update Many to Many Entity Framework . How do I do it?
... now in the Students collection of the Class, two entries will be inserted into the StudentClass table.
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Resolving LNK4098: defaultlib 'MSVCRT' conflicts with
...other linker errors is not uncommon. Things like errno, which is a extern int in the static CRT version but macro-ed to a function in the DLL version. Many others like that.
Well, fix this problem the Right Way, find the .obj or .lib file that you are linking that was compiled with the wrong /M o...