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How to configure Ruby on Rails with no database?
...o current need for a database. I know I could create an empty database in MySQL and go from there, but does anyone know a better way to run Rails without a database?
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On delete cascade with doctrine2
...rine's cascade={"remove"} removes the related entities before removing the root entity (it has to). So when the root entity is deleted there aren't any foreign relations left for onDelete="CASCADE" to delete. But to be sure I would suggest you simply create a small test case and look at the queries ...
How to print binary tree diagram?
... private static Node<Integer> test1() {
Node<Integer> root = new Node<Integer>(2);
Node<Integer> n11 = new Node<Integer>(7);
Node<Integer> n12 = new Node<Integer>(5);
Node<Integer> n21 = new Node<Integer>(2);
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Breadth First Vs Depth First
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Both kinds of traversal can be achieved with the pseudocode:
Store the root node in Container
While (there are nodes in Container)
N = Get the "next" node from Container
Store all the children of N in Container
Do some work on N
The difference between the two traversal orders lies in ...
Add a reference column migration in Rails 4
... Active Record only supports single column foreign keys and currently only mysql, mysql2 and PostgreSQL adapters are supported. Don't try this with other adapters like sqlite3, etc. Refer to Rails Guides: Foreign Keys for your reference.
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INSERT … ON DUPLICATE KEY (do nothing)
... uses resources for the second action.
Use INSERT IGNORE ...,
Negative : MySQL will not show any errors if something goes wrong, so you cannot handle the errors. Use it only if you don’t care about the query.
share
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Using vagrant to run virtual machines with desktop environment
...etter experience, I recommend these improvements:
Don't start the GUI as root. You really want to stay the vagrant user. To do this you need to permit anyone to start the GUI: sudo vim /etc/X11/Xwrapper.config and edit it to allowed_users=anybody.
Next, install the VirtualBox guest tools before st...
Having links relative to root?
Is there a way to have all links on a page be relative to the root directory?
6 Answers
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Mac zip compress without __MACOSX folder?
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To apply to all zip files under some root: find ~ -type f -name '*.zip' -exec zip -d '{}' __MACOSX/\* \;. Substitute your starting point for ~.
– Chris Johnson
Jun 27 '17 at 12:05
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Socket send函数和recv函数详解以及利用select()函数来进行指定时间的阻塞 ...
...有情况下，发送开始调用是局部的：无论其它进程的状态如何，它立刻返回。如果这个调用使得一些系统资源用完，那么它将失败并返回 一个错误代码。高质量的MPI实现应保证这种情况只在“病态”时发生。即，一个MPI实现将...