Tutorial by Examples: ai

Search and Return All Tables and Columns Containing a Specified Column Value

This script, from here and here, will return all Tables and Columns where a specified value exists. This is powerful in finding out where a certain value is in a database. It can be taxing, so it is suggested that it be executed in a backup / test enviroment first. DECLARE @SearchStr nvarchar(100) ...

Microsoft SQL Server • Retrieve information about the database

A fairly general function

We will use the built in tooth growth dataset. We are interested in whether there is a statistically significant difference in tooth growth when the guinea pigs are given vitamin C vs orange juice. Here's the full example: teethVC = ToothGrowth[ToothGrowth$supp == 'VC',] teethOJ = ToothGrowth[To...

R Language • Performing a Permutation Test

Add container to network

docker network connect app-backend myAwesomeApp-1 This command attaches the myAwesomeApp-1 container to the app-backend network. When you add a container to a user-defined network, the embedded DNS resolver (which is not a full-featured DNS server, and is not exportable) allows each container on ...

Docker • Docker network

Detach container from network

docker network disconnect app-backend myAwesomeApp-1 This command detaches the myAwesomeApp-1 container from the app-backend network. The container will no longer be able to communicate with other containers on the network it has been disconnected from, nor use the embedded DNS resolver to look u...

Docker • Docker network

Data-Only Containers

Data-only containers are obsolete and are now considered an anti-pattern! In the days of yore, before Docker's volume subcommand, and before it was possible to create named volumes, Docker deleted volumes when there were no more references to them in any containers. Data-only containers are obsolet...

Docker • Data Volumes and Data Containers

Detaching from a container

While attached to a running container with a pty assigned (docker run -it ...), you can press ControlP - ControlQ to detach.

Docker • Running containers

Docker container process debugging

Docker is just a fancy way to run a process, not a virtual machine. Therefore, debugging a process "in a container" is also possible "on the host" by simply examining the running container process as a user with the appropriate permissions to inspect those processes on the host (...

Docker • Debugging a container

Testing against a date range

Although it is very tempting to use BETWEEN ... AND ... for a date range, it is problematical. Instead, this pattern avoids most problems: WHERE x >= '2016-02-25' AND x < '2016-02-25' + INTERVAL 5 DAY Advantages: BETWEEN is 'inclusive' thereby including the final date or second. 2...

MySQL • Date and Time Operations

Consuming a Failed Future

Sometimes the computation in a Future can create an exception, which will cause the Future to fail. In the "Creating a Future" example, what if the calling code passed 55 and 0 to the divide method? It'd throw an ArithmeticException after trying to divide by zero, of course. How would t...

Scala Language • Futures

Reading a file into a container

In the example below we use std::string and operator>> to read items from the file. std::ifstream file("file3.txt"); std::vector<std::string> v; std::string s; while(file >> s) // keep reading until we run out { v.push_back(s); ...

C++ • File I/O

Insert mixed data into a JSON field.

This inserts a json dictionary where one of the members is an array of strings into the table that was created in another example. INSERT INTO myjson(dict) VALUES('{"opening":"Sicilian","variations":["pelikan","dragon","najdorf"]}'); ...

MySQL • JSON

execute command on lines that contain text

The :global command already has its own topic: The global command

vim • Searching in the current buffer

Wait for DOM to be loaded

Use DOMContentLoaded when the <script> code interacting with DOM is included in the <head> section. If not wrapped inside the DOMContentLoaded callback, the code will throw errors like Cannot read something of null document.addEventListener('DOMContentLoaded', function(event) { ...

DOM • Getting started with DOM

Create a Copy of an Object with Certain Changes

Case classes provide a copy method that creates a new object that shares the same fields as the old one, with certain changes. We can use this feature to create a new object from a previous one that has some of the same characteristics. This simple case class to demonstrates this feature: case cla...

Scala Language • Case Classes

Selecting a certain line from a list based on a word in certain location

I have the following list: 1. Alon Cohen 2. Elad Yaron 3. Yaron Amrani 4. Yogev Yaron I want to select the first name of the guys with the Yaron surname. Since I don't care about what number it is I'll just put it as whatever digit it is and a matching dot and space after it from the beginni...

Regular Expressions • Matching Simple Patterns

Traits to keep classes clean

Over time, our classes may implement more and more interfaces. When these interfaces have many methods, the total number of methods in our class will become very large. For example, let's suppose that we have two interfaces and a class implementing them: interface Printable { public functio...

PHP • Traits

Single precision and long double precision floating-point remainder: fmodf(), fmodl()

C99 These functions returns the floating-point remainder of the division of x/y. The returned value has the same sign as x. Single Precision: #include <math.h> /* for fmodf() */ #include <stdio.h> /* for printf() */ int main(void) { float x = 10.0; float y = 5.1; ...

C Language • Standard Math

Access the container view controller

When the view controller is presented within a tab bar controller, you can access the tab bar controller like this: Swift let tabBarController = viewController.tabBarController Objective-C UITabBarController *tabBarController = self.tabBarController; When the view controller is part on an n...

iOS • UIViewController

Change Rails timezone, but continue to have Active Record save in the database in UTC

# application.rb config.time_zone = 'Eastern Time (US & Canada)'

Ruby on Rails • Change default timezone

Change Rails timezone AND have Active Record store times in this timezone

# application.rb config.time_zone = 'Eastern Time (US & Canada)' config.active_record.default_timezone = :local

Ruby on Rails • Change default timezone