大约有 40,000 项符合查询结果（耗时：0.0597秒） [XML]
MySQL: @variable vs. variable. What's the difference?
... a procedure variable is reinitialized to NULL each time the procedure is called, while the session-specific variable is not:
CREATE PROCEDURE prc_test ()
BEGIN
DECLARE var2 INT DEFAULT 1;
SET var2 = var2 + 1;
SET @var2 = @var2 + 1;
SELECT var2, @var2;
END;
SET @var2 = 1;
CALL prc...
Return positions of a regex match() in Javascript?
... @OnurYıldırım - here's a jsfiddle of it working...I've tested it all the way back to IE5...works great: jsfiddle.net/6uwn1vof
– Jimbo Jonny
Mar 29 '16 at 22:34
1
...
How to import the class within the same directory or sub directory?
I have a directory that stores all the .py files.
13 Answers
13
...
Oracle “(+)” Operator
..."adding NULL values if no match found". For example, "a.id=b.id(+)" means allow b.id to be NULL if there is no match with a.id.
– beach
Oct 26 '10 at 5:00
...
data.table vs dplyr: can one do something well the other can't or does poorly?
...j and by together is by design. By keeping related operations together, it allows to easily optimise operations for speed and more importantly memory usage, and also provide some powerful features, all while maintaining the consistency in syntax.
1. Speed
Quite a few benchmarks (though mostly on g...
Difference between reduce and foldLeft/fold in functional programming (particularly Scala and Scala
...t is both commutative and associative. This means the operation can be parallelized.
This distinction is very important for Big Data / MPP / distributed computing, and the entire reason why reduce even exists. The collection can be chopped up and the reduce can operate on each chunk, then the red...
Jackson Vs. Gson [closed]
After searching through some existing libraries for JSON, I have finally ended up with these two:
5 Answers
...
Where can I locate themes for VS2012
...
New Theme editor Specifically for 2012:
http://visualstudiogallery.msdn.microsoft.com/366ad100-0003-4c9a-81a8-337d4e7ace05
Comes w/ VS 2010 style blue and a few others...
...
Coding Practices which enable the compiler/optimizer to make a faster program
...act.
Expect to be disappointed and to have to work very hard indeed for small performance improvements. Modern compilers for mature languages such as Fortran and C are very, very good. If you read an account of a 'trick' to get better performance out of code, bear in mind that the compiler writer...
Android存储系统基础知识：内部存储，外部存储，App特定目录 ASD(app speci...
...ative path) │ 完整路径(full path)
getASD代码实现
ASD vs 私有目录
« 返回首页
Android存储系统基础知识
英文原版链接→
Android存储系统概览图（图片模糊的话请拖动图片至新标签页打开）：
从 Android 的角度来看 →...