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“use database_name” command in PostgreSQL
...you must get a new connection.
Using \c in psql closes the old connection and acquires a new one, using the specified database and/or credentials. You get a whole new back-end process and everything.
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What are the disadvantages of using persistent connection in PDO
...rrent FastCGI process if you're using FastCGI, etc), not at the PHP level, and PHP doesn't tell the parent process to let the connection die when the script terminates abnormally.
If the dead script locked tables, those tables will remain locked until the connection dies or the next script that get...
What is the difference between static_cast and C style casting?
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C++ style casts are checked by the compiler. C style casts aren't and can fail at runtime.
Also, c++ style casts can be searched for easily, whereas it's really hard to search for c style casts.
Another big benefit is that the 4 different C++ style casts express the intent of the programm...
How can I escape a double quote inside double quotes?
...done by finishing an already-opened one ('), placing the escaped one (\'), and then opening another one (').
Alternatively:
$ echo 'abc'"'"'abc'
abc'abc
$ echo "abc"'"'"abc"
abc"abc
It's done by finishing already opened one ('), placing a quote in another quote ("'"), and then opening another on...
How to format a number as percentage in R?
...scales package, as documented in krlmlr's answer. Use that instead of my hand-rolled solution.
Try something like
percent <- function(x, digits = 2, format = "f", ...) {
paste0(formatC(100 * x, format = format, digits = digits, ...), "%")
}
With usage, e.g.,
x <- c(-1, 0, 0.1, 0.5555...
mongodb group values by multiple fields
...takes an "pipeline" expression as an argument instead of the "localFields" and "foreignFields" options. This then allows a "self-join" with another pipeline expression, in which we can apply $limit in order to return the "top-n" results.
db.books.aggregate([
{ "$group": {
"_id": "$addr",
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Escape text for HTML
...racters. See the accepted answer here: stackoverflow.com/a/4501246/1543677 and use both.
– pkExec
Dec 9 '14 at 11:46
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Query for documents where array size is greater than 1
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2.Create extra field NamesArrayLength, update it with names array length and then use in queries:
db.accommodations.find({"NamesArrayLength": {$gt: 1} });
It will be better solution, and will work much faster (you can create index on it).
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Exit Shell Script Based on Process Exit Code
I have a shell script that executes a number of commands. How do I make the shell script exit if any of the commands exit with a non-zero exit code?
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How to get the name of the current method from code [duplicate]
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And then there is CallerMemberNameAttribute stackoverflow.com/a/15310053/58768
– bohdan_trotsenko
Mar 17 '16 at 14:33
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