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How do SQL EXISTS statements work?
...hen tries to match this 'true/false' condition with outerquery." is what really cleared it up for me, I keep thinking that's how subqueries work (and many times they do), but what you said makes sense because the subquery relies on the outer query and therefore must be executed once per row
...
heroku - how to see all the logs
I have a small app on heroku. Whenever I want to see the logs I go to the command line and do
19 Answers
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How do I make and use a Queue in Objective-C?
...ject != nil) {
[[headObject retain] autorelease]; // so it isn't dealloc'ed on remove
[self removeObjectAtIndex:0];
}
return headObject;
}
// Add to the tail of the queue (no one likes it when people cut in line!)
- (void) enqueue:(id)anObject {
[self addObject:anObject]...
In git how is fetch different than pull and how is merge different than rebase?
...aving your local* branch unchanged.
pull will perform a fetch and additionally merge the changes into your local branch.
What's the difference? pull updates you local branch with changes from the pulled branch. A fetch does not advance your local branch.
merge vs rebase
Given the following histo...
HTTP 404 Page Not Found in Web Api hosted in IIS 7.5
...nted a solution that worked for me here.
At the end of the day, I enabled all verbs (verb="*") to the ExtensionlessUrlHandler-Integrated-4.0 handler in my web config.
<system.webServer>
<validation validateIntegratedModeConfiguration="false" />
<modules runAllManagedModulesF...
Why is `replace` property deprecated in AngularJS directives? [duplicate]
...PI docs , directives' replace attribute is deprecated, so in the future, all directives will behave with the current default of replace: false .
...
Output array to CSV in Ruby
...enerate_line(row) }.join("")
#=> "a1,a2,a3\nb1,b2,b3\nc1,c2,c3\n"
Do all of the above and save to a csv, in one line.
File.open("ss.csv", "w") {|f| f.write(rows.inject([]) { |csv, row| csv << CSV.generate_line(row) }.join(""))}
NOTE:
To convert an active record database to csv would...
Verify a certificate chain using openssl verify
...ing the first part of the post Greg references (the second part is specifically about pyOpenSSL and not relevant to this question).
In case the post goes away I'll quote the important paragraphs:
Unfortunately, an "intermediate" cert that is actually a root / self-signed
will be treated as a ...
git difftool, open all diff files immediately, not in serial
...
This feature works well with Meld 3.14.2 for example, and lets you browse all modified files:
git difftool --dir-diff --tool=meld HEAD~ HEAD
This is a handy Bash function:
git-diff-meld() (
git difftool --dir-diff --tool=meld "${1:-HEAD~}" "${2:-HEAD}"
)
The answer that follows applies to g...
Counting null and non-null values in a single query
...
If I understood correctly you want to count all NULL and all NOT NULL in a column...
If that is correct:
SELECT count(*) FROM us WHERE a IS NULL
UNION ALL
SELECT count(*) FROM us WHERE a IS NOT NULL
Edited to have the full query, after reading the comments :]
S...