Tutorial by Examples: co

Suppose we want to query the "cheapest products" from the "top categories". Here is an example of query using Common Table Expressions -- all_sales: just a simple SELECT with all the needed JOINS WITH all_sales AS ( SELECT product.price as product_price, category.id a...

With a column of one of the string types, named my_date_field with a value such as [the string] 07/25/2016, the following statement demonstrates the use of the STR_TO_DATE function: SELECT STR_TO_DATE(my_date_field, '%m/%d/%Y') FROM my_table; You could use this function as part of WHERE clause a...

Simple one-liners may be specified as command line arguments to perl using the -e switch (think "execute"): perl -e'print "Hello, World!\n"' Due to Windows quoting rules you can't use single-quoted strings but have to use one of these variants: perl -e"print qq(Hello, W...

With XML::Rabbit it is possible to consume XML files easily. You define in a declarative way and with an XPath syntax what you are looking for in the XML and XML::Rabbit will return objects according to the given definition. Definition: package Bookstore; use XML::Rabbit::Root; has_xpath_object_...

It is good practice to test the calling program's __name__ variable before executing your code. import sys def main(): # Your code starts here # Don't forget to provide a return code return 0 if __name__ == "__main__": sys.exit(main()) Using this pattern ens...

Adding components one after another results in a UI that's hard to use, because the components all are somewhere. The components are ordered from top to bottom, each component in a separate "row". To remedy this and provide you as developer with a possibility to layout components easily S...

curl -XGET 'http://www.example.com:9200/myIndexName/_count?pretty' Output: { "count" : 90, "_shards" : { "total" : 6, "successful" : 6, "failed" : 0 } } The index has 90 documents within it. Reference Link: Here

Let's say there's a collection called Todos and the autopublish package is added. Here is the basic component. import { createContainer } from 'meteor/react-meteor-data'; import React, { Component, PropTypes } from 'react'; import Todos from '/imports/collections/Todos'; export class List exte...

Before you compile your app and run it on your device, you'll need create some icons and splash screens, and add a mobile-config.js file to your app. App.icons({ // iOS 'iphone': 'resources/icons/icon-60x60.png', 'iphone_2x': 'resources/icons/[email protected]', 'ipad': 'resources/icons...

Now it's time to go through the Meteor Cordova Phonegap Integration documentation. Since that documentation was written, XCode and Yosemite have been released, which has caused some hiccups in installation. Here are the steps we had to go through to get Meteor compiled to an iOS device. Upgrade ...

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

The replica set will need an oplog user to access the database. mongo PRIMARY> use admin PRIMARY> db.addUser({user:"oplogger",pwd:"YOUR_PASSWORD",roles:[],otherDBRoles:{local:["read"]}}); PRIMARY> show users

The --url flag can be tricky to use. There is a 60 second window to authenticate, and then the username/password randomly resets. So be sure to have robomongo open and ready to configure a new connection when you run the command. # get the MONGO_URL string for your app meteor mongo --url $METEOR...

Same thing as before, but you have to copy the info into the mongodump command. You have to run the following commands rediculously fast, and it requires hand/eye coordination. Be warned! This is a rediculously hacky! But fun! Think of it as a video game! :D # get the MONGO_URL string for your app ...

Run meteor, open another terminal window, and run the following command. mongoexport --db meteor --collection foo --port 3001 --out foo.json

Mongo supports database-to-database copying, which is useful if you have large databases on a staging database that you want to copy into a local development instance. // run mongod so we can create a staging database // note that this is a separate instance from the meteor mongo and minimongo ins...

Preallocation. Mongo sets aside disk-space in empty containers, so when the time comes to write something to disk, it doesn't have to shuffle bits out of the way first. It does so by a doubling algorithm, always doubling the amount of disk space preallocated until it reaches 2GB; and then each preal...

Did you know about the --url flag? Very handy. meteor mongo --url YOURSITE.meteor.com

db.posts.find().forEach(function(doc){ db.posts.update({_id: doc._id}, {$set:{'version':'v1.0'}}, false, true); });

db.posts.find().forEach(function(doc){ if(doc.arrayOfObjects){ // the false, true at the end refers to $upsert, and $multi, respectively db.accounts.update({_id: doc._id}, {$unset: {'arrayOfObjects': "" }}, false, true); } });