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What's wrong with nullable columns in composite primary keys?
...ow in a table: when a table has a primary key, you have a guranteed way to select any row from it.
A unique constraint does not necessarily identify every row; it just specifies that if a row has values in its columns, then they must be unique. This is not sufficient to uniquely identify every row...
Xcode Project vs. Xcode Workspace - Differences
...nd resources) actually belong to a product. When you build/run, you always select one specific target.
It is likely that you have a few targets that share code and resources. These different targets can be slightly different versions of an app (iPad/iPhone, different brandings,…) or test cases th...
Remove Safari/Chrome textinput/textarea glow
... you can interact with. Let accessibility trump aesthetics here.
textarea, select, input, button { outline: none; }
Although, it's been argued that keeping the glow/outline is actually beneficial for accessibility as it can help users see which Element is currently focused.
You can also use the pse...
Change Bootstrap input focus blue glow
...
you forgot select
– David Morrow
Sep 4 '14 at 16:03
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show 6 more comments
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Finding ALL duplicate rows, including “elements with smaller subscripts”
...gt;% filter(n > 1) # data frame
df %>% add_count(col1, col2) %>% select(n) > 1 # logical vector
For duplicate rows (considering all columns):
df %>% group_by_all %>% add_tally %>% ungroup %>% filter(n > 1)
df %>% group_by_all %>% add_tally %>% ungroup %>% ...
Alternate table row color using CSS?
.../td>
</tr>
</tbody>
</table>
There is a CSS selector, really a pseudo-selector, called nth-child. In pure CSS you can do the following:
tr:nth-child(even) {
background-color: #000000;
}
Note: No support in IE 8.
Or, if you have jQuery:
$(document).ready(functi...
Failed to load c++ bson extension
...vailable when you installed your mongodb library. I suggest you do
xcode-select --install (on a mac)
or sudo apt-get install gcc make build-essential (on ubuntu)
and run
rm -rf node_modules
npm cache clean
npm install
OR just npm update based on @tobias comment (after installing build-essenti...
Get data from file input in JQuery
...tml>
<head>
<script>
function handleFileSelect()
{
if (!window.File || !window.FileReader || !window.FileList || !window.Blob) {
alert('The File APIs are not fully supported in this browser.');
return;
}
...
How can I load an object into a variable name that I specify from an R data file?
...
I'm extending the answer from @ricardo to allow selection of specific variable if the .Rdata file contains multiple variables (as my credits are low to edit an answer). It adds some lines to read user input after listing the variables contained in the .Rdata file.
loadRDa...
Empty Visual Studio Project?
...oject won't do a 'damn' thing either when you go to Project Properties and select Utility under Configuration Type under the General tab.
– Abel
Feb 2 '10 at 16:17
...