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Why does String.split need pipe delimiter to be escaped?
...lit is a regular expression, where in the '|' has a special meaning of OR, and a '\|' means a literal '|' so the string "\\|" means the regular expression '\|' which means match exactly the character '|'.
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Sqlite primary key on multiple columns
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@pratnala In standard SQL, yes. In SQLite, NULL is allowed in primary keys. This answer emphasizes that if you want more standard behavior, you need to add the NOT NULL yourself. My answer is just the very basic syntax for a multi-column pr...
Where can I view Tomcat log files in Eclipse?
... It refers to your workspace. In there you find a folder called .metadata and so on.
– Nils Schmidt
Feb 9 '10 at 23:08
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How to alias 'git checkout' to 'git co'
I'd like the command git co to be the same as typing git checkout .
3 Answers
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What is the difference between ArrayList.clear() and ArrayList.removeAll()?
...h faster since it doesn't have to deal with all those extra method calls.
And as Atrey points out, c.contains(..) increases the time complexity of removeAll to O(n2) as opposed to clear's O(n).
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Ruby on Rails: How can I revert a migration with rake db:migrate?
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Run the following command
rake db:migrate:down VERSION=<version>
where <version> is the version number of your migration file you want to revert.
eg. if you want to revert a migration with file name 3846656238_create_users.rb
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Make Font Awesome icons in a circle?
... the icon is rendered by CSS later: <i class="fa fa-lock"></i> and this is what @Schneider actually asked for.
– Jan
Nov 9 '14 at 0:09
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How do you perform a CROSS JOIN with LINQ to SQL?
....SelectMany(t1 => sequence2.Select(t2 => Tuple.Create(t1, t2)));
}
And use like:
vals1.CrossJoin(vals2)
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Is there an AddRange equivalent for a HashSet in C#
...dicate the distinct way the HashSet works. You cannot safely Add a set of random elements to it like in Collections, some elements may naturally evaporate.
I think that UnionWith takes its name after "merging with another HashSet", however, there's an overload for IEnumerable<T> too.
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How to add new column to MYSQL table?
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It's 2015 and people are still trying to set themselves up for sql injection vulnerabilities—:facepalm:
– CommandZ
Jul 8 '15 at 21:34
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