Category Archives: Programming

notes on how (not) to do programming

Group on table joins

Posted on February 14, 2020 by Robert

This is one of the more confusing issues of table joins. To make it extra confusing, try an outer join: Select * from ta as a left outer join tb as b on a.key = b.key Both tables have duplicate … Continue reading →

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How to select/display all rows with duplicate values in MySQL

Posted on December 3, 2017 by Robert

(This should be a fub, but the description is too long.) One of the most frequent uses of database tables is to identify duplicate values in your data. Assume you have a table with a list of names, and you … Continue reading →

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Capturing system command output in perl

Posted on April 11, 2017 by Robert

Running system commands from inside a perl script is one of the nastiest of all perl headaches. I suffered grievously when trying to use this method with some pdf file addons, and have scars to show for it. Lately, having … Continue reading →

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Fixing textwidth in vim

Posted on August 1, 2015 by Robert

I have had several problems with my program editor Vim recently. Here is how I fixed one of them. There are two directories that I had to mess with: c:\program files\vim [vim directory] c:\users\rabbit [user directory] the vim directory is … Continue reading →

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Mechanized Moodle

Posted on December 4, 2013 by Robert

One of the main things I use Perl for is to manage my grading chores on Chi Nan University’s Moodle system. Moodle is a very useful teaching tool, one I’ve been using for over 10 years. So if it’s such … Continue reading →

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