大约有 40,000 项符合查询结果（耗时：0.0472秒） [XML]
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...T(field) or COUNT(*), and stick with it consistently, and if your database allows COUNT(tableHere) or COUNT(tableHere.*), use that.
In short, don't use COUNT(1) for anything. It's a one-trick pony, which rarely does what you want, and in those rare cases is equivalent to count(*)
Use count(*) fo...
What is a “cache-friendly” code?
...her end of the memory spectrum (DRAM), the memory is very cheap (i.e. literally millions of times cheaper) but takes hundreds of cycles after a request to receive the data. To bridge this gap between super fast and expensive and super slow and cheap are the cache memories, named L1, L2, L3 in decre...
How do you see recent SVN log entries?
...n the given dates:
svn log -r {2011-02-02}:{2011-02-03}
You can combine all the above expressions with the --limit option, so that can you have a quite granular control over what is printed. For more info about these -r expressions refer to svn help log or the relevant chapter in the book Version...
Efficiency of Java “Double Brace Initialization”?
...2$8.class
2009/05/27 16:35 2,022 DemoApp2$9.class
These are all classes which were generated when I was making a simple application, and used copious amounts of anonymous inner classes -- each class will be compiled into a separate class file.
The "double brace initialization", as al...
How can I pretty-print JSON in a shell script?
...ou can use
curl http://my_url/ | python -m json.tool
For convenience in all of these cases you can make an alias:
alias prettyjson='python -m json.tool'
For even more convenience with a bit more typing to get it ready:
prettyjson_s() {
echo "$1" | python -m json.tool
}
prettyjson_f() {...
Rebuild or regenerate 'ic_launcher.png' from images in Android Studio
...
Beware using Asset Studio in Android Studio automatically adds padding, shrinking the resulting image.
– Androidcoder
Jun 16 '15 at 17:03
...
Python logging not outputting anything
...
@Ben where does it say that? All I can see is "The default level is WARNING, which means that only events of this level and above will be tracked, unless the logging package is configured to do otherwise."
– Omri Barel
...
Eclipse: The declared package does not match the expected package
...es of the project don't seem to be what Eclipse expects. The package names all have a prefix:
13 Answers
...
Ruby on Rails generates model field:type - what are the options for field:type?
...nother model's ID. I'd look it up myself, but I haven't figured out, among all my Ruby on Rails documentation links, how to find the definitive source.
...
How can I use tabs for indentation in IntelliJ IDEA?
...nvert tabs to spaces, you can chose "To Spaces" from the same place.
For all files
The paths in the other answers were changed a little:
File > Settings... > Editor > Code Style > Java > Tabs and Indents > Use tab character
File > Other Settings > Default Settings... &g...