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MySQL, Check if a column exists in a table with SQL
...pecific column, and if not — create it. Otherwise do nothing. This is really an easy procedure in any enterprise-class database, yet MySQL seems to be an exception.
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What is your single most favorite command-line trick using Bash? [closed]
We all know how to use <ctrl>-R to reverse search through history, but did you know you can use <ctrl>-S to forward search if you set stty stop "" ? Also, have you ever tried running bind -p to see all of your keyboard shortcuts listed? There are over 455 on Mac OS X by default. ...
Find an item in List by LINQ?
Here I have a simple example to find an item in a list of strings. Normally I use for loop or anonymous delegate to do it like this:
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How to crop an image in OpenCV using Python
...copy region of interest
If we consider (0,0) as top left corner of image called im with left-to-right as x direction and top-to-bottom as y direction. and we have (x1,y1) as the top-left vertex and (x2,y2) as the bottom-right vertex of a rectangle region within that image, then:
roi = im[y1:y2, x1...
How do I concatenate strings and variables in PowerShell?
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This isn't technically concatenation.
– TravisEz13
Jun 14 '16 at 17:59
9
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How to generate .NET 4.0 classes from xsd?
...or the case you have several interlinked schema definitions just name them all. xsd schema1.xsd schema2.xsd schema3.xsd /c
– mivra
Oct 24 '16 at 19:40
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sendmail: how to configure sendmail on ubuntu? [closed]
...guration are located at the following (in case you want to update them manually):
/etc/mail/sendmail.conf
/etc/cron.d/sendmail
/etc/mail/sendmail.mc
You can test sendmail to see if it is properly configured and setup by typing the following into the command line:
$ echo "My test email being sent...
What's the 'Ruby way' to iterate over two arrays at once
...e an expression like that, it's always best to use parentheses for method calls, just in case. @budget.zip(@actual).each
– AboutRuby
Aug 26 '10 at 22:48
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View/edit ID3 data for MP3 files
...roperties (FirstArtist, Artist, JointedArtists, FirstPerformer) and almost all of them are read-only or deprecated...
– Laserson
Oct 14 '10 at 17:24
3
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'and' (boolean) vs '&' (bitwise) - Why difference in behavior with lists vs numpy arrays?
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and tests whether both expressions are logically True while & (when used with True/False values) tests if both are True.
In Python, empty built-in objects are typically treated as logically False while non-empty built-ins are logically True. This facilitates the c...