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I need to generate uuid for my rails application. What are the options(gems) I have? [duplicate]
... the column.
Example in Rails 3 migration
execute <<-SQL
CREATE TABLE some_items (id uuid PRIMARY KEY DEFAULT uuid_generate_v1());
SQL
Might be a better way to do this in Rails 4.
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UITableViewCell with UITextView height in iOS 7?
How can I calculate the height of an UITableViewCell with an UITextView in it in iOS 7?
12 Answers
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How do I replace NA values with zeros in an R dataframe?
...the complete results.
If you are struggling with massive dataframes, data.table is the fastest option of all: 40% faster than the standard Base R approach. It also modifies the data in place, effectively allowing you to work with nearly twice as much of the data at once.
A clustering of other he...
grep using a character vector with multiple patterns
...attern = 'A1|A9|A6', x = myfile$Letter)
Or even more simply:
library(data.table)
myfile$Letter %like% 'A1|A9|A6'
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How is Math.Pow() implemented in .NET Framework?
...plemented in the CLR, written in C++. The just-in-time compiler consults a table with internally implemented methods and compiles the call to the C++ function directly.
Having a look at the code requires the source code for the CLR. You can get that from the SSCLI20 distribution. It was written arou...
brew install mysql on macOS
... like there is something wrong with the set up instructions or the initial tables that are being created. This is how I got mysqld running on my machine.
If the mysqld server is already running on your Mac, stop it first with:
launchctl unload -w ~/Library/LaunchAgents/com.mysql.mysqld.plist
Star...
How to install mongoDB on windows?
...st imagine an SQL server or Oracle Db with entirely different rows in same table? Is it possible in our relational DB table? This is how mongo works. I will show you how we can do that…
First I will show you how the data will look in a relational DB.
For example consider an Employee table and a S...
Linear Regression and group by in R
...factor are your variables. Please keep in mind that Your.df must be a data.table class
– FraNut
Nov 17 '15 at 9:33
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Why switch is faster than if
...h switch the JVM loads the value to compare and iterates through the value table to find a match, which is faster in most cases.
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how to generate migration to make references polymorphic
I have a Products table and want to add a column:
4 Answers
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