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Why does Oracle 9i treat an empty string as NULL?
I know that it does consider ' ' as NULL , but that doesn't do much to tell me why this is the case. As I understand the SQL specifications, ' ' is not the same as NULL -- one is a valid datum, and the other is indicating the absence of that same information.
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Using group by on multiple columns
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Group By X means put all those with the same value for X in the one group.
Group By X, Y means put all those with the same values for both X and Y in the one group.
To illustrate using an example, let's say we have the following table, to do with who is attending what subject at a univers...
How to call methods dynamically based on their name? [duplicate]
How can I call a method dynamically when its name is contained in a string variable? For example:
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Unix tail equivalent command in Windows Powershell
...f Unix command tail for Windows Powershell. A few alternatives available on are,
13 Answers
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IN vs OR in the SQL WHERE Clause
... = 'b' OR foo = 'c'
According to the manual for MySQL if the values are constant IN sorts the list and then uses a binary search. I would imagine that OR evaluates them one by one in no particular order. So IN is faster in some circumstances.
The best way to know is to profile both on your datab...
How to set HTTP headers (for cache-control)?
How to enable browser caching for my site? Do I just put cache-control:public somewhere up in my header like this?
8 Answer...
Convert a PHP script into a stand-alone windows executable
...the command line using PHP-CLI. Now I want to hand over this script to someone but I do not want to:
7 Answers
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What does “Could not find or load main class” mean?
A common problem that new Java developers experience is that their programs fail to run with the error message: Could not find or load main class ...
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Print only?
How do I print the indicated div (without manually disabling all other content on the page)?
30 Answers
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Import existing source code to GitHub
... source code you want to add to a new remote new git repository without 'cloning' the remote first, do the following (I often do this - you create your remote empty repository in bitbucket/github, then push up your source)
Create the remote repository, and get the URL such as git@github.com:/youru...