Tutorial by Examples: e

Given this data: dateamount2016-03-122002016-03-11-502016-03-141002016-03-151002016-03-10-250 SELECT date, amount, SUM(amount) OVER (ORDER BY date ASC) AS running FROM operations ORDER BY date ASC will give you dateamountrunning2016-03-10-250-2502016-03-11-50-3002016-03-12200-1002016-03-1410...

use feature qw( say ); # Numbers are true if they're not equal to 0. say 0 ? 'true' : 'false'; # false say 1 ? 'true' : 'false'; # true say 2 ? 'true' : 'false'; # true say -1 ? 'true' : 'false'; # true say 1-1 ? 'true' : 'false'; # fa...

var line = 0 var maximum_lines = 5 while (line < maximum_lines) { line = line + 1 println("Line number: " + line) }

var line = 0 var maximum_lines = 5 do { line = line + 1 println("Line number: " + line) } while (line < maximum_lines) The do/while loop is infrequently used in functional programming, but can be used to work around the lack of support for the break/continue construct, as...

Breakpoints pause your program once execution reaches a certain point. You can then step through the program line by line, observing its execution and inspecting the contents of your variables. There are three ways of creating breakpoints. From code, using the debugger; statement. From the brow...

The pipe operator, %>%, is used to insert an argument into a function. It is not a base feature of the language and can only be used after attaching a package that provides it, such as magrittr. The pipe operator takes the left-hand side (LHS) of the pipe and uses it as the first argument of the ...

3.0 Check if a string consists in exactly 8 digits: $ date=20150624 $ [[ $date =~ ^[0-9]{8}$ ]] && echo "yes" || echo "no" yes $ date=hello $ [[ $date =~ ^[0-9]{8}$ ]] && echo "yes" || echo "no" no

You can indent the text inside here documents with tabs, you need to use the <<- redirection operator instead of <<: $ cat <<- EOF This is some content indented with tabs `\t`. You cannot indent with spaces you __have__ to use tabs. Bash will remove empty space befo...

2.05b You can feed a command using here strings like this: $ awk '{print $2}' <<< "hello world - how are you?" world $ awk '{print $1}' <<< "hello how are you > she is fine" hello she You can also feed a while loop with a here string: $ while IFS...

Use putAll to put every member of one map into another. Keys already present in the map will have their corresponding values overwritten. Map<String, Integer> numbers = new HashMap<>(); numbers.put("One", 1) numbers.put("Three", 3) Map<String, Integer> othe...

To begin making modifications to the project's data, you have to obtain a local copy of the versioned project. Use the command line svn client or your favorite SVN client (TortoiseSVN, for example). Your local copy of the project is called a working copy in Subversion and you get it by issuing the c...

If you want to get the versioned project's data, but you don't need any of the version control capabilities offered by Subversion, you could run svn export <URL> command. Here is an example: $ svn export https://svn.example.com/svn/MyRepo/MyProject/trunk As a result, you will get the proje...

A a pointer to a piece of memory containing n elements may only be dereferenced if it is in the range memory and memory + (n - 1). Dereferencing a pointer outside of that range results in undefined behavior. As an example, consider the following code: int array[3]; int *beyond_array = array + 3; ...

git log -S"#define SAMPLES" Searches for addition or removal of specific string or the string matching provided REGEXP. In this case we're looking for addition/removal of the string #define SAMPLES. For example: +#define SAMPLES 100000 or -#define SAMPLES 100000 git log -G&q...

To delete a remote branch in Git: git push [remote-name] --delete [branch-name] or git push [remote-name] :[branch-name]

If a remote branch has been deleted, your local repository has to be told to prune the reference to it. To prune deleted branches from a specific remote: git fetch [remote-name] --prune To prune deleted branches from all remotes: git fetch --all --prune

Listed from least expensive to most expensive at run-time: str::strtok is the cheapest standard provided tokenization method, it also allows the delimiter to be modified between tokens, but it incurs 3 difficulties with modern C++: std::strtok cannot be used on multiple strings at the same t...

A wide variety of standard library functions have among their effects copying byte sequences from one memory region to another. Most of these functions have undefined behavior when the source and destination regions overlap. For example, this ... #include <string.h> /* for memcpy() */ ch...

Requirements: OS X 10.8 “Mountain Lion” or newer required to run Docker. While the docker binary can run natively on Mac OS X, to build and host containers you need to run a Linux virtual machine on the box. 1.12.0 Since version 1.12 you don't need to have a separate VM to be installed, as Docker...

To uninstall one or more locally installed packages, use: npm uninstall <package name> The uninstall command for npm has five aliases that can also be used: npm remove <package name> npm rm <package name> npm r <package name> npm unlink <package name> npm un ...