大约有 31,840 项符合查询结果（耗时：0.0329秒） [XML]
entity object cannot be referenced by multiple instances of IEntityChangeTracker. while adding relat
... @Maritim it depends on the usage. In Web Applications, its typically one roundtrip. In Desktop Applications, you might also use one per Form (what ever, it just represents one unit of work) per Thread (because DbContext is not guaranteed to be threadsafe).
– LuckyLikey
...
How to select the rows with maximum values in each group with dplyr? [duplicate]
...) per group while the OP's ddply approach with which.max would only return one maximum (the first) per group. To replicate that behavior, another option is to use slice(which.max(value)) in dplyr.
– talat
Jun 25 '15 at 7:23
...
How to create a video from images with FFmpeg?
...u encounter problems, such as the first image is skipped or only shows for one frame, then use the fps video filter instead of -r for the output framerate
ffmpeg -r 1/5 -i img%03d.png -c:v libx264 -vf fps=25 -pix_fmt yuv420p out.mp4
Alternatively the format video filter can be added to the fi...
How do I declare a namespace in JavaScript?
...The important point is to be religious about expanding no further than the one root variable. Everything must flow from this.
– annakata
May 19 '09 at 8:54
22
...
Why use sprintf function in PHP?
...f has all the formatting capabilities ... actually is missing an important one, %,8d for instance to get the rightly aligned 8 digit and commas separated integer. Using number_format is less convenient in a printf style.
– e2-e4
Nov 16 '10 at 6:41
...
What is a “Bitmap heap scan” in a query plan?
...our comment... Yep, that's exactly it.
An index scan will go through rows one by one, opening disk pages again and again, as many times as necessary (some will of course stay in memory, but you get the point).
A bitmap index scan will sequentially open a short-list of disk pages, and grab every ap...
How to define a two-dimensional array?
...array type with two dimensions. There are many ways to create a new array; one of the most useful is the zeros function, which takes a shape parameter and returns an array of the given shape, with the values initialized to zero:
>>> import numpy
>>> numpy.zeros((5, 5))
array([[ 0....
Bootstrap carousel multiple frames at once
...
Can this be done with bootstrap 3's carousel? I'm hoping I won't have
to go hunting for yet another jQuery plugin
As of 2013-12-08 the answer is no. The effect you are looking for is not possible using Bootstrap 3's generic carousel p...
AngularJS : How to watch service variables?
... not sure how this is a better solution than $watch, the questioner was asking for a simple way of sharing the data, it looks even more cumbersome. I would rather use $broadcast than this
– Jin
Feb 27 '14 at 6:32
...
How to prevent Node.js from exiting while waiting for a callback?
...hat occurs, allowing node to exit silently.
This is a sneaky bug, that is one that the module developer might not run into during development, as it will occur less often in busy systems with many queues as it will be rare for all of them to be empty at the critical time.
A possible fix/bug detect...