By default, migrations are applied to the same database specified by the db application component. If you want them to be applied to a different database, you may specify the db command-line option like shown below:
yii migrate --db=db2
yii migrate/history # showing the last 10 applied migrations
yii migrate/history 5 # showing the last 5 applied migrations
yii migrate/history all # showing all applied migrations
yii migrate/new # showing the first 10 new migrations
yii migrate/new 5 # showing the first 5 ...
yii migrate/mark 150101_185401 # using timestamp to specify the migration
yii migrate/mark "2015-01-01 18:54:01" # using a string that can be parsed by strtotime()
yii migrate/mark m150101_185401_create_news_table # using full name
yii migrate/mark 13...
yii migrate
This command will list all migrations that have not been applied so far. If you confirm that you want to apply these migrations, it will run the up() or safeUp() method in every new migration class, one after another, in the order of their timestamp values. If any of the migrations fa...
An abstract class is a class that cannot be instantiated. Abstract classes can define abstract methods, which are methods without any body, only a definition:
abstract class MyAbstractClass {
abstract public function doSomething($a, $b);
}
Abstract classes should be extended by a child cla...
A simple bit-field can be used to describe things that may have a specific number of bits involved.
struct encoderPosition {
unsigned int encoderCounts : 23;
unsigned int encoderTurns : 4;
unsigned int _reserved : 5;
};
In this example we consider an encoder with 23 bits of sin...
SELECT *
FROM
table1,
table2
SELECT
table1.column1,
table1.column2,
table2.column1
FROM
table1,
table2
This is called cross product in SQL it is same as cross product in sets
These statements return the selected columns from multiple tables in one query....
Set memory limit and disable swap limit
docker run -it -m 300M --memory-swap -1 ubuntu:14.04 /bin/bash
Set both memory and swap limit. In this case, container can use 300M memory and 700M swap.
docker run -it -m 300M --memory-swap 1G ubuntu:14.04 /bin/bash
WCF tracing is built on top of System.Diagnostics. To use tracing, you should define trace sources in the configuration file or in code.
Tracing is not enabled by default. To activate tracing, you must create a trace listener and set a trace level other than "Off" for the selected trace s...
We can use Predefined Constants for Date format in date() instead of the conventional date format strings since PHP 5.1.0.
Predefined Date Format Constants Available
DATE_ATOM - Atom (2016-07-22T14:50:01+00:00)
DATE_COOKIE - HTTP Cookies (Friday, 22-Jul-16 14:50:01 UTC)
DATE_RSS - RSS (Fri, 22...
Installation Requirements
The minimum requirement by this project template is that your Web server supports PHP 5.4.0.
Yii2-advanced-app can be installed in two ways. They are
Installing via Composer
Installing from an Archive File
1) Installing via Composer
If you do not already have Comp...
First, download the compiler and components.
Next, add Swift to your path. On macOS, the default location for the downloadable toolchain is /Library/Developer/Toolchains. Run the following command in Terminal:
export PATH=/Library/Developer/Toolchains/swift-latest.xctoolchain/usr/bin:"${PATH}...
Technically, autoloading works by executing a callback when a PHP class is required but not found. Such callbacks usually attempt to load these classes.
Generally, autoloading can be understood as the attempt to load PHP files (especially PHP class files, where a PHP source file is dedicated for a ...
An anonymous function is just a function that doesn't have a name.
// Anonymous function
function() {
return "Hello World!";
};
In PHP, an anonymous function is treated like an expression and for this reason, it should be ended with a semicolon ;.
An anonymous function should b...
In PHP, an anonymous function has its own scope like any other PHP function.
In JavaScript, an anonymous function can access a variable in outside scope. But in PHP, this is not permitted.
$name = 'John';
// Anonymous function trying access outside scope
$sayHello = function() {
return &q...
A closure is an anonymous function that can't access outside scope.
When defining an anonymous function as such, you're creating a "namespace" for that function. It currently only has access to that namespace.
$externalVariable = "Hello";
$secondExternalVariable = "Foo&qu...
A std::vector can be useful for returning a dynamic number of variables of the same type. The following example uses int as data type, but a std::vector can hold any type that is trivially copyable:
#include <vector>
#include <iostream>
// the following function returns all integers...
