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When should one use final for method parameters and local variables?
...e set by end of construction, making that field reference immutable. This allows safe publication of fields and can avoid the need for synchronization on later reads. (Note that for an object reference, only the field reference is immutable - things that object reference refers to can still change...
How do I get SUM function in MySQL to return '0' if no values are found?
...iddle.com/#!2/d1542/3/0
More Information:
Given three tables (one with all numbers, one with all nulls, and one with a mixture):
SQL Fiddle
MySQL 5.5.32 Schema Setup:
CREATE TABLE foo
(
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
val INT
);
INSERT INTO foo (val) VALUES
(null),(1),(n...
How do I create a file AND any folders, if the folders don't exist?
...
You can blindly call Directory.CreateDirectory without the Directory.Exists check first - it won't throw if the directory is already there.
– Tim Robinson
Jul 8 '10 at 8:14
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Execute command on all files in a directory
...rovide the code to do the following:
Assume there is a directory of files, all of which need to be run through a program. The program outputs the results to standard out. I need a script that will go into a directory, execute the command on each file, and concat the output into one big output file.
...
How can I find non-ASCII characters in MySQL?
...ame WHERE columnToCheck NOT REGEXP '[A-Za-z0-9]';
That query will return all rows where columnToCheck contains any non-alphanumeric characters. If you have other characters that are acceptable, add them to the character class in the regular expression. For example, if periods, commas, and hyphens ...
Rails ActiveRecord date between
...
I would personally created a scope to make it more readable and re-usable:
In you Comment.rb, you can define a scope:
scope :created_between, lambda {|start_date, end_date| where("created_at >= ? AND created_at <= ?", start_date, e...
How to use PHP OPCache?
PHP 5.5 has been released and it features a new code caching module called OPCache, but there doesn't appear to be any documentation for it.
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API Versioning for Rails Routes
...Bo Jeanes for the prompting on those things.
You might want to wear a really strong helmet because this is going to blow your mind.
The Rails 3 routing API is super wicked. To write the routes for your API, as per your requirements above, you need just this:
namespace :api do
namespace :v1 d...
How to truncate a foreign key constrained table?
...ata integrity.
Option 1:
Remove constraints
Perform TRUNCATE
Delete manually the rows that now have references to nowhere
Create constraints
Option 2: suggested by user447951 in their answer
SET FOREIGN_KEY_CHECKS = 0;
TRUNCATE table $table_name;
SET FOREIGN_KEY_CHECKS = 1;
...
Understanding Fragment's setRetainInstance(boolean)
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First of all, check out my post on retained Fragments. It might help.
Now to answer your questions:
Does the fragment also retain its view state, or will this be recreated on configuration change - what exactly is "retained"?
Y...