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MySQL pagination without double-querying?
...nt for a few seconds and that will help a lot.
The other way is to use SQL_CALC_FOUND_ROWS clause and then call SELECT FOUND_ROWS(). apart from the fact you have to put the FOUND_ROWS() call afterwards, there is a problem with this: There is a bug in MySQL that this tickles that affects ORDER BY qu...
Mean per group in a data.frame [duplicate]
... object. It’s easier to do what you’re after with dplyr: d %>% group_by(Name) %>% mutate(mean1=mean(Rate1), mean2=mean(Rate2))
– jbaums
May 29 '19 at 9:48
...
PostgreSQL naming conventions
...valent convention is:
SQL keywords: UPPER CASE
names (identifiers): lower_case_with_underscores
For example:
UPDATE my_table SET name = 5;
This is not written in stone, but the bit about identifiers in lower case is highly recommended, IMO. Postgresql treats identifiers case insensitively whe...
Editing legend (text) labels in ggplot
... text in the legend, even though it's in my dataframe. I have tried scale_colour_manual , scale_fill_manual with different values for labels= such as c("T999", "T888")", "cols" .
...
Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize
...d was moved to native memory.
So in order to remove this message
edit MAVEN_OPTS Environment User Variable:
Java 7
MAVEN_OPTS -Xmx512m -XX:MaxPermSize=128m
Java 8
MAVEN_OPTS -Xmx512m
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C/C++ NaN constant (literal)?
...
In C, NAN is declared in <math.h>.
In C++, std::numeric_limits<double>::quiet_NaN() is declared in <limits>.
But for checking whether a value is NaN, you can't compare it with another NaN value. Instead use isnan() from <math.h> in C, or std::isnan() from <c...
PHP Multidimensional Array Searching (Find key by specific value)
...
Another poossible solution is based on the array_search() function. You need to use PHP 5.5.0 or higher.
Example
$userdb=Array
(
(0) => Array
(
(uid) => '100',
(name) => 'Sandra Shush',
(url) => 'urlof100'
),
(1) => Array
...
java.lang.OutOfMemoryError: bitmap size exceeds VM budget - Android
... meminfo command. If you see heap usage increasing over a few gc cycles (GC_* log row in logcat) you can be pretty sure you have a leak. Then create a heap dump (or several at different times) via adb or DDMS and analyze it via the dominator tree tooling on Eclipse MAT. You should pretty soon find w...
Find and restore a deleted file in a Git repository
...mmit, this commit must have deleted it.
git rev-list -n 1 HEAD -- <file_path>
Then checkout the version at the commit before, using the caret (^) symbol:
git checkout <deleting_commit>^ -- <file_path>
Or in one command, if $file is the file in question.
git checkout $(git re...
Why should I use Google's CDN for jQuery?
...icrosoft - https://docs.microsoft.com/en-us/aspnet/ajax/cdn/overview#jQuery_Releases_on_the_CDN_0]2
jsDelivr - https://www.jsdelivr.com/package/npm/jquery
code.jquery.com (StackPath) - https://code.jquery.com/
Google - https://developers.google.com/speed/libraries/#jquery
But to sum it up, you are...