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How to count occurrences of a column value efficiently in SQL?
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If you're using Oracle, then a feature called analytics will do the trick. It looks like this:
select id, age, count(*) over (partition by age) from students;
If you aren't using Oracle, then you'll need to join back to the counts:
select a.id, a.age, b.age_co...
How do I get the current time zone of MySQL?
...ng the web server and the DB server it's talking to are set to [if not actually in] the same timezone isn't a huge leap.) But beware that (as with MySQL), you can set the timezone that PHP uses (date_default_timezone_set), which means it may report a different value than the OS is using. If you're i...
Is there a “do … while” loop in Ruby?
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It looks like the begin-end-while loop is actually evaluating the condition before running the loop. The difference between that and a regular while loop is that it's guaranteed to run at least once. It's just close enough to do...while to cause problems.
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Test if a class has an attribute?
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to only check if the attribute is present, which is usually all that is needed for parameterless/propertyless attributes, it's cheaper to use .IsDefined, as it will query the metadata, and not deserialize and instantiate the attribute object.
– Lasse V. Karl...
Disable Maven warning message - “Selected war files include a WEB-INF/web.xml which will be ignored”
...if you are happy with the default web.xml then don't write one yourself at all.
– Ustaman Sangat
Oct 17 '12 at 16:07
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What is the difference between .map, .every, and .forEach?
I've always wondered what the difference between them were. They all seem to do the same thing...
4 Answers
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Select objects based on value of variable in object using jq
...t work: termux-contact-list |jq -r '.[] | select(.name=="$1")|.number'. I call it like cool_fn Name1. However, this works: termux-contact-list |jq -r '.[] | select(.name=="Name1")|.number'
– Timo
Aug 18 '18 at 8:13
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Properly escape a double quote in CSV
...le double quote to escape a double quote. You can use a command-line tool called csvfix to detect any lines which don't conform: csvfix check -nl -v [filename]
– Sam Critchley
Jun 30 '16 at 14:51
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AsyncTask threads never die
...uriosity, why is it designed like that? Why not just end the threads after all of the methods have returned?
– Computerish
Jun 20 '10 at 2:38
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LEFT JOIN vs. LEFT OUTER JOIN in SQL Server
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Absolutely correct. OUTER is allowed for ANSI-92 compatibility.
– Sean Reilly
Jan 2 '09 at 21:34
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