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Want to find records with no associated records in Rails
...).where( :friends => { :person_id => nil } )
For the hmt it's basically the same thing, you rely on the fact that a person with no friends will also have no contacts:
Person.includes(:contacts).where( :contacts => { :person_id => nil } )
Update
Got a question about has_one in the c...
How to calculate date difference in JavaScript?
... 24 hours, and any 'variation' in that due to Daylight Savings Time is actually a switch of timezones. If you don't distinguish between timezones already, trying to figure out a time difference is going to put you in a world of hurt, not least because the DST switchover 'repeats' time. Stay in one t...
What are '$$' used for in PL/pgSQL
...c to function definitions. It can be used to replace single quotes practically anywhere in SQL scripts.
The body of a function happens to be a string literal which has to be enclosed in single quotes. Dollar-quoting is a PostgreSQL-specific substitute for single quotes to avoid quoting issues insi...
MySQL connection not working: 2002 No such file or directory
...dPress. I have Apache and MySQL running, and the accounts and database are all set up. I tried to make a simple connection:
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Best practices for overriding isEqual: and hash
...ly attributed to Dan Bernstein or Chris Torek. That older algorithm originally floated around on Usenet, and certain attribution is difficult. For example, there is some interesting commentary in this Apache code (search for their names) that references the original source.
Bottom line is, this i...
Is there a MySQL command to convert a string to lowercase?
...of keywords that are presently mixed-case. However, I want to convert them all to lowercase. Is there an easy command to do this, either using MySQL or MySQL and PHP?
...
Eclipse interface icons very small on high resolution screen in Windows 8.1
...rious icons and buttons in the Eclipse (Kepler) interface are very, very small on a laptop with a 3200x1800px screen. The red error decoration that appears to indicate errors on files is difficult to see unless my nose a few cm from the screen.
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How do I create a custom Error in JavaScript?
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I'm still a bit lost in all those prototype things. Why in your example you assign name to this.name and not to NotImplementedError.prototype.name? Can you answer please, it's crucial for my understanding :)
– jayarjo
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Better to 'try' something and catch the exception or test if it's possible first to avoid an excepti
...est option when the index is probably in the list and the IndexError is usually not raised. This way you avoid the need for an extra lookup by if index < len(my_list).
Python encourages the use of exceptions, which you handle is a phrase from Dive Into Python. Your example not only handles the e...
Transitioning from Windows Forms to WPF
...pply them with the data needed.
Because of this, the designer isn't actually used that much since your application components are designed in code, and the designer is only needed to draw a user-friendly interface that reflects your data classes (typically Models and ViewModels)
And personally, ...