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Rails migration: t.references with alternative name?
...n with this:
add_foreign_key :courses, :courses, column: :transferrable_as_id
add_foreign_key :courses, :courses, column: :same_as_id
Update
In Rails 5.1 and above you can add the foreign key in the migration in the create_table block like this:
create_table :courses do |t|
t.string :name
t.ref...
quick random row selection in Postgres
...
You might want to experiment with OFFSET, as in
SELECT myid FROM mytable OFFSET floor(random()*N) LIMIT 1;
The N is the number of rows in mytable. You may need to first do a SELECT COUNT(*) to figure out the value of N.
Update (by Antony Hatchkins)
You must use floor here:
SELE...
jQuery checkbox checked state changed event
I want an event to fire client side when a checkbox is checked / unchecked:
10 Answers
...
Getting the IP address of the current machine using Java
... command line parameter.
In summary, InetAddress.getLocalHost() will typically work, but you may need to provide an alternative method for the cases where your code is run in an environment with "complicated" networking.
I am able to get all the IP addresses associated all Network Interfaces...
Simple way to copy or clone a DataRow?
... Note: If you'll be *reusing* the aux. table for single-row cloning later, call
// tableAux.Clear() first.
tableAux.ImportRow(row);
// Extract the cloned row from the aux. table:
var rowClone = tableAux.Rows[0];
Note: Shallow cloning is performed, which works as-is with column values that a...
Why doesn't Java allow overriding of static methods?
...m of Smalltalk about it being too slow (garbage collection and polymorphic calls being part of that) and Java's creators were determined to avoid that. Another was the decision that the target audience for Java was C++ developers. Making static methods work the way they do had the benefit of familia...
【精心整理】【实用】visual C++中最常用的类与API函数 - C/C++ - 清泛网 -...
...个CArchive对象
CArchive(CFile* pFile,UINT nMode,int nBufSize=4096,void* lpBuf=NULL);
参数：pFile 指向CFile对象的指针，这个CFile对象是数据的最终源或目的；
nMode是标志，取值为CArchive::load时，从文档中加载数据（要求CFile读许可），取值为CArch...
水果vs蔬菜智能分类器 - EdgeML图像识别项目 · App Inventor 2 中文网
... TP/(TP+FP)
避免误报
>0.85
召回率 (Recall)
TP/(TP+FN)
避免漏报
>0.85
F1分数
2(PR)/(P+R)
综合评价
>0.85
特异性 (Specificity)
TN/(TN+FP)
负样本识别
>0.90
...
Recommended date format for REST GET API
...mplies that recommendation for date type in RFC 3986 should be used.
Basically RFC 3339 Date and Time on the Internet is the document to look at that says:
date and time format for use in Internet protocols that is a
profile of the ISO 8601 standard for representation of dates and
t...
static allocation in java - heap, stack and permanent generation
...method get stored.
If you mean the value returned by a (non-void) method call, then it is either returned on the stack or in a machine register. If it is returned on the stack, this takes 1 or two words, depending on the return type.
7) If the objects (in the young generation) nees to use a s...