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Counting null and non-null values in a single query
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This works for Oracle and SQL Server (you might be able to get it to work on another RDBMS):
select sum(case when a is null then 1 else 0 end) count_nulls
, count(a) count_not_nulls
from us;
Or:
select count(*) - count(a), count(a) fro...
How can I compare two lists in python and return matches
I want to take two lists and find the values that appear in both.
19 Answers
19
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In PHP, how do you change the key of an array element?
...r it is not a sequential numerical value. The key is actually an ID number and the value is a count. This is fine for most instances, however I want a function that gets the human-readable name of the array and uses that for the key, without changing the value.
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Git diff -w ignore whitespace only at start & end of lines
...if you want a built in solution.
However, if you don't mind getting your hands dirty there's a rather old patch floating out there somewhere that adds support for "--ignore-space-at-sol".
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Returning null as an int permitted with ternary operator but not if statement
...itional operator (as described in the Java Language Specification, 15.25), and moves happily on. This will generate a NullPointerException at run time, which you can confirm by trying it.
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im...
Getting parts of a URL (Regex)
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A single regex to parse and breakup a
full URL including query parameters
and anchors e.g.
https://www.google.com/dir/1/2/search.html?arg=0-a&arg1=1-b&arg3-c#hash
^((http[s]?|ftp):\/)?\/?([^:\/\s]+)((\/\w+)*\/)([\w\-\.]+[^#?\s...
Convert NSNumber to int in Objective-C
...mplicit conversion is now disallowed with ARC.
– Alexander
Nov 21 '17 at 12:52
basically [key intValue] (key is NSNumb...
Math.random() explanation
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int randomWithRange(int min, int max)
{
int range = (max - min) + 1;
return (int)(Math.random() * range) + min;
}
Output of randomWithRange(2, 5) 10 times:
5
2
3
3
2
4
4
4
5
4
The bounds are inclusive, ie [2,5], an...
Find location of a removable SD card
...le via USB Mass Storage mode when mounted on a host machine", at least for Android 1.x and 2.x.
But the question is about external SD. How to get a path like "/mnt/sdcard/external_sd" (it may differ from device to device)?
Android has no concept of "external SD", aside from external storage, as de...
Write string to output stream
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Streams (InputStream and OutputStream) transfer binary data. If you want to write a string to a stream, you must first convert it to bytes, or in other words encode it. You can do that manually (as you suggest) using the String.getBytes(Charset) ...