You have to create a derived table for the distinct columns and then query the count from that table:
***
SELECT COUNT(*)
FROM (SELECT DISTINCT column1,column2
FROM tablename
WHERE condition ) as dt
***
Here dt is a derived table.

***DELETE from search
where id not in (
select min(id) from search
group by url
having count(*)=1

union

SELECT min(id) FROM search
group by url
having count(*) > 1
)***

Invoking dev.off() to make RStudio open up a new graphics device with default settings worked for me. HTH.

You can sometimes get this if you accidentally import/embed the same JavaScript file twice, worth checking in your resources tab of the inspector.

*** ob_start();
var_dump($_POST['C']);
$result = ob_get_clean();
?>***
if you want to capture the result in a variable

For Windows, when you install a package, you type:
***python -m pip install [packagename]***

Personally I find this to be the most clean - not sure if it's the most efficient, mind!
***if (is_array($values) || is_object($values))
{
foreach ($values as $value)
{
...
}
}***
The reason for my preference is it doesn't allocate an empty array when you've got nothing to begin with anyway.

I'm surprised no one's mentioned this yet: CSS transitions.

You can natively transition a div's background image:
***
#some_div {
background-image:url(image_1.jpg);
-webkit-transition:background-image 0.5s;
/* Other vendor-prefixed transition properties */
transition:background-image 0.5s;
}
***
***#some_div:hover {
background-image:url(image_2.jpg);
}***
This saves any kind of JavaScript or jQuery animation to fade an 's src.

Ensures that the object is displayed (or should be) only to readers and similar devices. It give more sense in context with other element with attribute aria-hidden="true".
***

***
Glyphicon will be displayed on all other devices, word Error: on text readers.

You can use CSS 3 :before to have a semi-transparent background and you can do this with just one container. Use something like this

***

Text.

***
Then apply some CSS

***article {
position: relative;
z-index: 1;
}

article::before {
content: "";
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
opacity: .4;
z-index: -1;
background: url(path/to/your/image);
}***

The easy and effective solution is trying .contains method.
***test.classList.contains(testClass);***

If you use all of the following, it will work in most browsers except Internet Explorer.
***.foo {
background-image: url(bg-image.png);
-moz-background-size: 100% 100%;
-o-background-size: 100% 100%;
-webkit-background-size: 100% 100%;
background-size: 100% 100%;
} ***