大约有 40,000 项符合查询结果（耗时：0.0587秒） [XML]
Is it possible to roll back CREATE TABLE and ALTER TABLE statements in major SQL databases?
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http://wiki.postgresql.org/wiki/Transactional_DDL_in_PostgreSQL:_A_Competitive_Analysis provides an overview of this issue from PostgreSQL's perspective.
Is DDL transactional according to this document?
PostgreSQL - yes
MySQL - no; DDL causes an implicit commit
Oracl...
Merge / convert multiple PDF files into one PDF
...eir order is preserved by "*". If its not preserved, using ranges: filename_{0..9}.pdf solves it.
– lepe
Jan 5 '15 at 5:48
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show 18 more co...
How do I append text to a file?
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better sudo rm -r / than sudo rm -rf /! ^_^ Is there a flag that would ask for confirmation before overwriting the contents of an existing file with >? Aliasing that to always use such a flag seems like it would be a good idea.
– sixty4bit
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Add a custom attribute to a Laravel / Eloquent model on load?
...this->getMutatedAttributes() as $key)
{
if ( ! array_key_exists($key, $array)) {
$array[$key] = $this->{$key};
}
}
return $array;
}
public function getUpperAttribute()
{
return strtoupper($this->title); ...
Summarizing multiple columns with dplyr? [duplicate]
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The dplyr package contains summarise_all for this aim:
library(dplyr)
df %>% group_by(grp) %>% summarise_all(list(mean))
#> # A tibble: 3 x 5
#> grp a b c d
#> <int> <dbl> <dbl> <dbl> <dbl>
#>...
Replace selector images programmatically
... = new StateListDrawable();
states.addState(new int[] {android.R.attr.state_pressed},
getResources().getDrawable(R.drawable.pressed));
states.addState(new int[] {android.R.attr.state_focused},
getResources().getDrawable(R.drawable.focused));
states.addState(new int[] { },
getResources()....
Setting JDK in Eclipse
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I had to change my JAVA_HOME environment variable to the JDK's folder too, and the JRE was not enough.
– Noumenon
Sep 10 '15 at 0:57
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Logger slf4j advantages of formatting with {} instead of string concatenation
...ogger,so that it avoids string concatenation?
– a3.14_Infinity
Nov 26 '14 at 10:46
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Easily measure elapsed time
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//***C++11 Style:***
#include <chrono>
std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();
std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
std::cout << "Time difference = " << std::chrono::duration_cast<std::c...
Export query result to .csv file in SQL Server 2008
... the following to be the best option
PowerShell Script
$dbname = "**YOUR_DB_NAME_WITHOUT_STARS**"
$AttachmentPath = "c:\\export.csv"
$QueryFmt= @"
**YOUR_QUERY_WITHOUT_STARS**
"@
Invoke-Sqlcmd -ServerInstance **SERVER_NAME_WITHOUT_STARS** -Database $dbname -Query $QueryFmt | Export-CSV $Attac...