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How to add column if not exists on PostgreSQL?
...lumn_name> <column_type>;
EXCEPTION
WHEN duplicate_column THEN RAISE NOTICE 'column <column_name> already exists in <table_name>.';
END;
END;
$$
You can't pass these as parameters, you'll need to do variable substitution in the string on the clie...
How to initialize HashSet values by construction?
..." and "b". Note that while in JDK 8 this does return a HashSet, the specification doesn't guarantee it, and this might change in the future. If you specifically want a HashSet, do this instead:
Set<String> set = Stream.of("a", "b")
.collect(Collectors.toCollection(Hash...
How to use Checkbox inside Select Option
...heckbox" size="5">
<option>Dog</option>
<option>Cat</option>
<option>Hippo</option>
<option>Dinosaur</option>
<option>Another Dog</option>
</select>
<h3>Font Awesome</h3>
<select multiple="" class...
How do I set a variable to the output of a command in Bash?
...equired, just for readability.
About sudo cmd | grep ... | cut ...
shell=$(cat /etc/passwd | grep $USER | cut -d : -f 7)
echo $shell
/bin/bash
(Please avoid useless cat! So this is just one fork less:
shell=$(grep $USER </etc/passwd | cut -d : -f 7)
All pipes (|) implies forks. Where another pr...
What exactly does Perl's “bless” do?
...t common case), to an array (not so common), to a scalar (usually this indicates an inside-out object), to a regular expression, subroutine or TYPEGLOB (see the book Object Oriented Perl: A Comprehensive Guide to Concepts and Programming Techniques by Damian Conway for useful examples) or even a ref...
When do Java generics require
...extend T. If the List contains Animals, the List can contain both Dogs and Cats (both Animals). Dogs have a property "woofVolume" and Cats have a property "meowVolume." While we might like to sort based upon these properties particular to subclasses of T, how can we expect this method to do that? A ...
How to search a specific value in all tables (PostgreSQL)?
... 18 '11 at 11:55
Mike Sherrill 'Cat Recall'Mike Sherrill 'Cat Recall'
78.5k1616 gold badges103103 silver badges156156 bronze badges
...
Retrieve specific commit from a remote Git repository
...push.sh:
git fetch --depth=1 ../testrepo/.git $SHA1
You can use the git cat-file command to see that the commit has been fetched:
git cat-file commit $SHA1
"git upload-pack" that serves "git fetch" can be told to serve
commits that are not at the tip of any ref, as long as they are
reac...
MySQL foreign key constraints, cascade delete
...
If your cascading deletes nuke a product because it was a member of a category that was killed, then you've set up your foreign keys improperly. Given your example tables, you should have the following table setup:
CREATE TABLE categories (
id int unsigned not null primary key,
name VA...
How do I completely uninstall Node.js, and reinstall from beginning (Mac OS X)
....nodejs.node.pkg.bom >> ~/filelist.txt
Manually review your file (located in your Home folder)
~/filelist.txt
Then delete the files:
cat ~/filelist.txt | while read f; do sudo rm /usr/local/${f}; done
sudo rm -rf /usr/local/lib/node /usr/local/lib/node_modules /var/db/receipts/org.nodejs.*...