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Validate uniqueness of multiple columns
... the following example:
database table records are supposed to be unique by n fields;
multiple (two or more) concurrent requests, handled by separate processes each (application servers, background worker servers or whatever you are using), access database to insert the same record in table;
each ...
How to open a web server port on EC2 instance
... @Noitidart Save is what he means. But I am sure you figured that out by now :)
– mattdevio
Oct 26 '18 at 7:31
Th...
How to create a protocol with methods that are optional?
...ier for a method after compilation. You can provide the correct identifier by using the @selector() directive and specifying the name of the method.
If the data source in this example implements the method, the title is used; otherwise, the title remains nil.
...
An efficient way to transpose a file in Bash
...$ ./shell.sh
0 3 6 9
1 4 7 10
2 5 8 11
Performance against Perl solution by Jonathan on a 10000 lines file
$ head -5 file
1 0 1 2
2 3 4 5
3 6 7 8
4 9 10 11
1 0 1 2
$ wc -l < file
10000
$ time perl test.pl file >/dev/null
real 0m0.480s
user 0m0.442s
sys 0m0.026s
$ time awk -f ...
Where is nodejs log file?
...
There is no log file. Each node.js "app" is a separate entity. By default it will log errors to STDERR and output to STDOUT. You can change that when you run it from your shell to log to a file instead.
node my_app.js > my_app_log.log 2> my_app_err.log
Alternatively (recommended...
How to read a file in Groovy into a string?
... Do I have to execute some close() statements or will the reader be closed by the getText() method?
– das Keks
Apr 29 '14 at 8:27
6
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微博为什么限制140字(附短信70字限制考) - 闲聊区 - 清泛IT社区，为创新赋能！
...sage. We reserve 20 characters for people’s names, and the other 140 are all yours! (via Twitter FAQ)也就是说，twitter希望微博首先能做到“微”，言简意赅，其次这样的限制是考虑到短信更新状态的字数限制，本身是160字母的限制，再留20字给id长度...
Choosing Mobile Web HTML5 Framework [closed]
...ut the merits, but jQuery mobile (though it is in alpha as well) is backed by a strong team and a community of supporters by extension of the core jQuery library. Probably the best choice for anything except the most enterprise centric applications.
Titanium:
Titanium is not an HTML5 mobile framewo...
Entity Framework 4 - AddObject vs Attach
...e value of the EntityKey is used to update (or delete) the appropriate row by finding its matching ID in the db table.
Furthermore, using the Attach method, you can define relationships between entities that already exist in the ObjectContext but that have not been connected automatically. Basical...
Func with out parameter
...nd V as covariant. However, since a parameter (output) of type U is passed by reference, U cannot be marked co- or contravariant and must remain "invariant". So consider public delegate V MyDelegate<in T, U, out V>(T input, out U output); if you use C# 4 or later.
– Jeppe...