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In Ruby on Rails, what's the difference between DateTime, Timestamp, Time and Date?
...ith Rails and everything to do with whatever database you're using.
Using MySQL as an example (if for no other reason because it's most popular), you have DATE, DATETIME, TIME and TIMESTAMP column data types; just as you have CHAR, VARCHAR, FLOAT and INTEGER.
So, you ask, what's the difference? We...
What is the most efficient way of finding all the factors of a number in Python?
...s will return all of the factors, very quickly, of a number n.
Why square root as the upper limit?
sqrt(x) * sqrt(x) = x. So if the two factors are the same, they're both the square root. If you make one factor bigger, you have to make the other factor smaller. This means that one of the two will ...
A complete solution to LOCALLY validate an in-app receipts and bundle receipts on iOS 7
... NSURL *certificateURL = [[NSBundle mainBundle] URLForResource:@"AppleIncRootCertificate" withExtension:@"cer"];
NSData *certificateData = [NSData dataWithContentsOfURL:certificateURL];
if ([self verifyPKCS7:p7 withCertificateData:certificateData])
{
struct pkcs7_st *contents =...
ImportError: No module named pip
...mpted to install the nova client.
spencers-macbook-pro:python-novaclient root# python setup.py install
running install
/usr/bin/python: No module named pip
error: /usr/bin/python -m pip.__init__ install 'pbr>=0.5.21,<1.0' 'iso8601>=0.1.4' 'PrettyTable>=0.6,<0.8' 'requests>...
'IF' in 'SELECT' statement - choose output value based on column values
...IF(type = 'P', amount, amount * -1) as amount
FROM report
See http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html.
Additionally, you could handle when the condition is null. In the case of a null amount:
SELECT id,
IF(type = 'P', IFNULL(amount,0), IFNULL(amount,0) * -1) as...
Find and Replace Inside a Text File from a Bash Command
... I stumbled over this...
There is a replace command which ships with the "mysql-server" package, so if you have installed it try it out:
# replace string abc to XYZ in files
replace "abc" "XYZ" -- file.txt file2.txt file3.txt
# or pipe an echo to replace
echo "abcdef" |replace "abc" "XYZ"
See m...
Favourite performance tuning tricks [closed]
...
Assuming MySQL here, use EXPLAIN to find out what is going on with the query, make sure that the indexes are being used as efficiently as possible and try to eliminate file sorts. High Performance MySQL: Optimization, Backups, Replica...
How to exit in Node.js
... encounter, including Unix shells like Bash, the shells for databases like MySQL and PostgreSQL, and the REPLs for programming languages like Python, PHP, and Ruby. It is the only method of exiting shells I ever use.
– Mark Amery
May 23 '15 at 22:52
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How can I get the current network interface throughput statistics on Linux/UNIX? [closed]
...
This assumes root access is available
– Lionel
Nov 7 '11 at 4:18
20
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Should I commit or rollback a read transaction?
...timization points for your app. If you're really curious, you can find the mySQL transaction handling code at bazaar.launchpad.net/~mysql/mysql-server/mysql-6.0/annotate/…
– Mark Brackett
May 21 '10 at 15:05
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