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Add unique constraint to combination of two columns
I have a table and, somehow, the same person got into my Person table twice. Right now, the primary key is just an autonumber but there are two other fields that exist that I want to force to be unique.
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Creating my own Iterators
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You should use Boost.Iterators. It contains a number of templates and concepts to implement new iterators and adapters for existing iterators. I have written an article about this very topic; it's in the December 2008 ACCU magazine. It discusses an (IMO) elegant solution for exactly your pr...
What are the differences between .gitignore and .gitkeep?
What are the differences between .gitignore and .gitkeep ? Are they the same thing with a different name, or do they both serve a different function?
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Will the base class constructor be automatically called?
...e -> Most Derived.
So in your particular instance, it calls Person(), and then Customer() in the constructor orders. The reason why you need to sometimes use the base constructor is when the constructors below the current type need additional parameters. For example:
public class Base
{
p...
Best practices for SQL varchar column length [closed]
...t into it, not the max length you define. So from a storage point of view (and most probably a performance one as well), it does not make any difference whether you declare a column as VARCHAR(100) or VARCHAR(500).
You should see the max length provided for a VARCHAR column as a kind of constraint...
How to upgrade PostgreSQL from version 9.6 to version 10.1 without losing data?
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Assuming you've used home-brew to install and upgrade Postgres, you can perform the following steps.
Stop current Postgres server:
launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
Initialize a new 10.1 database:
initdb /usr/local/var/postgre...
Depend on a branch or tag using a git URL in a package.json?
Say I've forked a node module with a bugfix and I want to use my fixed version, on a feature branch of course, until the bugfix is merged and released.
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Returning from a finally block in Java
... it's "better," consider the developer who has to maintain your code later and who might not be aware of the subtleties. That poor developer might even be you....
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Should I hash the password before sending it to the server side?
... is a silver bullet, which it is not. It certainly helps greatly however, and should be used in any authenticated session.
There is really no need to know what an original password is. All that is required is a reliable way to generate (and reliably re-generate) an authentication "key" based on t...
How does this giant regex work?
...e nicely done. Basically, it lists all the files in the current directory, and it lets you change directories.
4 Answers
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