Tutorial by Examples: co

innodb_buffer_pool_size should be about 70% of available RAM.

x IN ( SELECT ... ) turn into a JOIN When possible, avoid OR. Do not 'hide' an indexed column in a function, such as WHERE DATE(x) = ...; reformulate as WHERE x = ... You can generally avoid WHERE LCASE(name1) = LCASE(name2) by having a suitable collation. Do no use OFFSET for "paginatio...

Example below shows how to create a BroadcastReceiver which is able to receive BOOT_COMPLETED events. This way, you are able to start a Service or start an Activity as soon device was powered up. Also, you can use BOOT_COMPLETED events to restore your alarms since they are destroyed when device is ...

For a Django project with requirements and deployment tools under source control. This example builds upon concepts from the Two Scoops of Django. They have published a template: repository/ docs/ .gitignore project/ apps/ blog/ migrations/ ...

One of the nicest features of flexbox is to allow optimally fitting containers to their parent element. Live demo. HTML: <div class="flex-container"> <div class="flex-item">1</div> <div class="flex-item">2</div> <div class=&q...

Sometimes you may need to validate record only under certain conditions. class User < ApplicationRecord validates :name, presence: true, if: :admin? def admin? conditional here that returns boolean value end end If you conditional is really small, you can use a Proc: class ...

Imagine that we have a separate Google spreadsheet, and we need to get the B2 cell value to cell D5 on your current sheet. function copyValueandPaste() { var source = SpreadsheetApp.openById('spread sheet id is here'); //Separate spreadsheet book var sourcesheet = source.getSheetByName...

As with docopt, with [docopt_dispatch] you craft your --help in the __doc__ variable of your entry-point module. There, you call dispatch with the doc string as argument, so it can run the parser over it. That being done, instead of handling manually the arguments (which usually ends up in a high c...

We request that the Chef community not use this StackOverflow documentation feature. Docs managed via wiki (or community editing in general) tend to rot very quickly and are of poor quality. We've all experienced the sense of dread when searching for an answer on Google and getting back a half-unrea...

An array column is supported by PostgreSQL. Rails will automatically convert a PostgreSQL array to a Ruby array, and vice-versa. Create a table with an array column: create_table :products do |t| t.string :name t.text :colors, array: true, default: [] end Add an array column to an existi...

https://github.com/jaymedavis/stripe.net is a great starting point. Assuming you are using MVC w/Razor you need to have a few things in your View page <script type="text/javascript" src="https://js.stripe.com/v2/"></script> This script calls upon the stripe.js t...

It's good practice to complete your AssemblyInfo's default fields. The information may be picked up by installers and will then appear when using Programs and Features (Windows 10) to uninstall or change a program. The minimum should be: AssemblyTitle - usually the namespace, i.e. MyCompany.MySo...

This example shows how a MongoDB collection can be displayed in a React component. The collection is continuously synchronized between server and client, and the page instantly updates as database contents change. To connect React components and Meteor collections, you'll need the react-meteor-data...

Then go into the mongo shell and initiate the replica set, like so: meteor mongo > rs.initiate() PRIMARY> rs.add("mongo-a") PRIMARY> rs.add("mongo-b") PRIMARY> rs.add("mongo-c") PRIMARY> rs.setReadPref('secondaryPreferred')

Knitr is an R package that allows us to intermingle R code with LaTeX code. One way to achieve this is external code chunks. External code chunks allow us to develop/test R Scripts in an R development environment and then include the results in a report. It is a powerful organizational technique....

FunctionWidgetactionButtonAction ButtoncheckboxGroupInputA group of check boxescheckboxInputA single check boxdateInputA calendar to aid date selectiondateRangeInputA pair of calendars for selecting a date rangefileInputA file upload control wizardhelpTextHelp text that can be added to an input form...

A very useful feature many people overlook is the ability to construct a Map using a SOQL query. Map<Id, Account> accounts = new Map<Id, Account>([SELECT Id, Name FROM Account]); System.debug(accounts); When you run this code, accounts then contains a Map of your Account objects, ke...

You can clear the console window using the console.clear() method. This removes all previously printed messages in the console and may print a message like "Console was cleared" in some environments.

Intuition The categorical product of two types A and B should contain the minimal information necessary to contain inside an instance of type A or type B. We can see now that the intuitive coproduct of two types should be Either a b. Other candidates, such as Either a (b,Bool), would contain a part...

First thing to do is enable the mod rewrite on wamp go to Apache modules and scroll down the list If not showing tick enable it and then restart all servers. Linux users can also use below terminal command to enable rewrite module sudo a2enmod rewrite Then restart apache using: sudo service...