border-bottom: 3px dashed orange;

The above style is a shorthand property of the following three properties:

border-bottom-width: 20px; 
border-bottom-style: dotted; 
border-bottom-color: blue;

font: bold italic 14px Tahoma;

The above style is a shorthand property of the following four properties:

font-weight: bold; 
font-style:italic; 
font-size: 14px; 
font-family: Tahoma;

We can also search for more than one term by passing multiple arguments

composer search keyword1 keyword2

In JSON: Array values must be of type

string

,

number

,

object

,

array

,

boolean

or

null

... In JavaScript: Array values can be all of the above, plus any other valid JavaScript expression, including

functions

,

dates

,

undefined

,

symbol

Creates

backup.sql

backup file of

some_db

database using

some_user

MySQL user. The database is located at

34.mysql.servage.net

server.

mysqldump -h 34.mysql.servage.net -u some_user -p some_db > backup.sql

Creates

backup.sql

backup file of

some_db

database with the same MySQL user but without

-h

flag. If the database is located on the same server (localhost)

-h

flag is not necessary to specify

mysqldump -u some_user -p some_db > backup.sql

If we want to include all the routines (procedures, functions), then we need to use flag

-R

mysqldump -u some_user -p some_db -R > backup.sql

If we want to export only one or several tables, then we should list tables after database name

mysqldump -u root -p sdtokens sdt_prices another_table > sdt_prices.sql

After running the command, we will be required to enter password of the

some_user

mysql user. After that, MySQL will create

backup.sql

file on the same location

Method chaining technique gives us ability to call several methods with only one PHP expression (in one go)

class Bill {
    public $dinner = 20;
    public $dessert = 5;
    public $drink = 3;
    
    public $bill = 0;
    
    public function dinner($count) {
        $this->bill += $count * $this->dinner;
        return $this;
    }
    public function dessert($count) {
        $this->bill += $count * $this->dessert;
        return $this;
    }
    public function drink($count) {
        $this->bill += $count * $this->drink;
        return $this;
    }
}

$bill = new Bill;

We can call several methods one by one and print the

$bill

:

$bill->dinner(3); 
$bill->dessert(2);
$bill->drink(1);
echo $bill->bill;

Or we can combine the above 4 expressions using method chaining. The result will be the same:

echo $bill->dinner(3)->dessert(2)->drink(1)->bill;

Installs exactly the specified version of the module

npm install moment@2.25.2

Installs the specified module with the latest

patch

npm install moment@2.25

Installs the specified module with the latest

minor

and

patch

versions

npm install moment@1

Installs the latest version of the module (with latest

major

,

minor

and

patch

versions)

npm install moment

The drag and drop feature lets you

grab

an object and drag it to a different location. To make an element draggable, we set the

draggable

attribute to true. JS

function allowDrop(ev) {
    ev.preventDefault();
}
function drag(ev) {
    ev.dataTransfer.setData("text", ev.target.id);
}
function drop(ev) {
    ev.preventDefault();
    var data = ev.dataTransfer.getData("text");
    ev.target.appendChild(document.getElementById(data));
}

HTML

<div id="box" ondrop="drop(event)" ondragover="allowDrop(event)" style="border:1px solid black; width:200px; height:200px"></div>

<img id="image" src="https://image.shutterstock.com/image-photo/large-beautiful-drops-transparent-rain-260nw-668593321.jpg" draggable="true" ondragstart="drag(event)" width="150" height="50" alt="" />

Several ways to call non-static method from static method: One way is to use

new

keyword followed by the class name

(new Foo)->nonStaticMethod();

Another method is to use

self

which comes after

new

keyword

(new self)->nonStaticMethod();

Complete example:

class Foo {

    public function nonStaticMethod()
    {
        return 'non-static';
    }

    public static function staticMethod()
    {
        // return (new Foo)->nonStaticMethod();
        return (new self)->nonStaticMethod();
    }
}

echo Foo::staticMethod();

The second method

new self

is better, because if we want to rename the class later, we will not need to change the class name more than one place

Select students with

gmail

account. Using

IF

statement:

SELECT * 
FROM `students` 
WHERE IF(LENGTH(mail), mail, mail2) LIKE '%gmail.com%'
ORDER BY points

Using

OR

logical operator:

SELECT *
FROM  `students` 
WHERE 
    (`mail` LIKE '%gmail.com%' AND LENGTH(mail))
    OR 
    (mail2 LIKE '%gmail.com%') 
ORDER BY points

Using

CASE

SELECT * 
FROM `students` 
WHERE 
    (CASE
        WHEN LENGTH(mail) THEN mail
        ELSE mail2
    END) LIKE '%gmail.com%'
ORDER BY points