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Index on multiple columns in Ruby on Rails
...columns in sequence starting at the beginning. i.e. if you index on [:user_id, :article_id], you can perform a fast query on user_id or user_id AND article_id, but NOT on article_id.
Your migration add_index line should look something like this:
add_index :user_views, [:user_id, :article_id]
...
TypeScript: problems with type system
...ave a problem with its type system. My html site has a canvas tag with the id "mycanvas". I'm trying to draw a rectangle on this canvas. Here's the code
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How to move an element into another element?
I would like to move one DIV element inside another. For example, I want to move this (including all children):
15 Answers
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How to use Checkbox inside Select Option
...lect Option menu containing a checkbox together with the item name as individual items in the list.
Is there anyway possible to add a checkbox inside a Select Option menu?
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Styling an input type=“file” button
...the input will not respond to the likes of:
<input type="file" style="width:200px">
Instead, you will need to use the size attribute:
<input type="file" size="60" />
For any styling more sophisticated than that (e.g. changing the look of the browse button) you will need to look at ...
How to open a local disk file with JavaScript?
...
function displayContents(contents) {
var element = document.getElementById('file-content');
element.textContent = contents;
}
document.getElementById('file-input')
.addEventListener('change', readSingleFile, false);
<input type="file" id="file-input" />
<h3>Contents of the file:...
Android - implementing startForeground for a service?
...
@Snicolas: Thank you for pointing out a flaw in Android. I will work on getting this fixed.
– CommonsWare
Oct 12 '12 at 15:19
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Can I have multiple primary keys in a single table?
...made from two or more columns. For example:
CREATE TABLE userdata (
userid INT,
userdataid INT,
info char(200),
primary key (userid, userdataid)
);
Update: Here is a link with a more detailed description of composite primary keys.
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URL rewriting with PHP
...RewriteEngine on
RewriteRule ^/?Some-text-goes-here/([0-9]+)$ /picture.php?id=$1
This will tell Apache to enable mod_rewrite for this folder, and if it gets asked a URL matching the regular expression it rewrites it internally to what you want, without the end user seeing it. Easy, but inflexible,...
How to insert values into C# Dictionary on instantiation?
...gt;()
{
{ 111, new StudentName {FirstName="Sachin", LastName="Karnik", ID=211}},
{ 112, new StudentName {FirstName="Dina", LastName="Salimzianova", ID=317}},
{ 113, new StudentName {FirstName="Andy", LastName="Ruth", ID=198}}
};
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