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How do I automatically sort a has_many relationship in Rails?
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You can specify the sort order for the bare collection with an option on has_many itself:
class Article < ActiveRecord::Base
has_many :comments, :order => 'created_at DESC'
end
class Comment < ActiveRecord::Base
belongs_to :article
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Why does the order in which libraries are linked sometimes cause errors in GCC?
Why does the order in which libraries are linked sometimes cause errors in GCC?
9 Answers
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Select random row from a sqlite table
...a look at Selecting a Random Row from an SQLite Table
SELECT * FROM table ORDER BY RANDOM() LIMIT 1;
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Order discrete x scale by frequency/value
... ggplot with discrete x scale, the x axis are now arranged in alphabetical order, but I need to rearrange it so that it is ordered by the value of the y-axis (i.e., the tallest bar will be positioned on the left).
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How to get cumulative sum
...om @t t1
inner join @t t2 on t1.id >= t2.id
group by t1.id, t1.SomeNumt
order by t1.id
SQL Fiddle example
Output
| ID | SOMENUMT | SUM |
-----------------------
| 1 | 10 | 10 |
| 2 | 12 | 22 |
| 3 | 3 | 25 |
| 4 | 15 | 40 |
| 5 | 23 | 63 |
Edit: this...
Order of member constructor and destructor calls
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In other words, are members guaranteed to be initialized by order of declaration and destroyed in reverse order?
Yes to both. See 12.6.2
6 Initialization shall proceed in the
following order:
First, and only for
the constructor of the most derived
class as described below, virtual ...
How important is the order of columns in indexes?
...umn 2 in the Join or Search Predicate then it would not be beneficial. So order matters there also. Maybe that goes without saying, but wanted to mention it.
– CodeCowboyOrg
Mar 23 '15 at 16:15
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How do SQL EXISTS statements work?
...way:
For 'each' row from Suppliers, check if there 'exists' a row in the Order table that meets the condition Suppliers.supplier_id (this comes from Outer query current 'row') = Orders.supplier_id. When you find the first matching row, stop right there - the WHERE EXISTS has been satisfied.
The ...
NUnit Test Run Order
...tests run alphabetically. Does anyone know of any way to set the execution order? Does an attribute exist for this?
16 Answ...
MySQL get row position in ORDER BY
...sition
FROM TABLE t
JOIN (SELECT @rownum := 0) r
ORDER BY t.name) x
WHERE x.name = 'Beta'
...to get a unique position value. This:
SELECT t.id,
(SELECT COUNT(*)
FROM TABLE x
WHERE x.name <= t.name) AS position,
t.name
FROM TABLE...