1.php introduction

• php is a back-end language. Is a server language. Run on the server side
• PHP is the suffix of PHP. We can understand the code
• The main goal is to allow web developers to quickly write dynamic page numbers

2. Basic grammar

• php can be placed anywhere in the document. With <? php starts with? > ending.

	<?php
	#Here is the code
	   ?>

• PHP statements end with a semicolon.

3. Notes

	<?php
		// Single-Line Comments 
		
		# Single-Line Comments 
		
		/*
		multiline comment 
		*/ 
	?>

4. Variables

	<?php
		// Solve the problem of garbled code
		    header('Content-type:text/html;charset=utf-8')
		// Define variables
		    $name = 'Zhang San';
		// output
	    echo $name;
	 ?>

Variable rule

• The variable starts with the $sign, followed by the variable name
• Variable names must start with letters or underscores
• Variable names cannot start with numbers
• Variable names are case sensitive
• Variable names can only contain alphanumeric underscores

php output

• echo – can output more than one string
• print - returns 1 when the output is successful and 0 when the output fails
• var_dump() – the function is used to output variables and display the structured information of variables

5.php data type

	<?php
		$num = 234;
		var_dump($num); // Integer int(234)
		
		$num1 = 234.1;
		var_dump($num1); // Floating point number float(234.1)
		
		$num2 = ture;
		var_dump($num2) // bool(true)
    ?>

6.PHP array

Array stores multiple values in a variable

	Array creation method 1:
	    stay PHP In the array, the value stored in the element can be any data type
	    $arr[0] = 123;
		$arr[1] = 23.23;
		$arr[2] = 'hello'
	    $arr[3] = true
	ergodic
	for($i=0;i<count($arr).length;$i++){
	    echo '<br>'.$arr[$i]
	}
	Mode 2:
	    $arr = array('hello','hi')

7.PHP functions

	<?php
	   function test($num1,$num2){
	    $res = $num1+$num2;
	    return $res;
		} 
    ?>

8.PHP objects

An object is a data type that stores data and information about how data is processed

In PHP, objects must be explicitly declared

The class of the object must be declared, using the class keyword. A class is a structure that contains properties and methods

	<?php
		    calss Car
		{
		    public $name;
		    public $age;
		    public function speak($str){
		        echo 'What is this'.$str;
		    }
		}
		// Instantiate object
		$p1 = new Person();
		$p1->name = 'Xiaobai'
		$p2->age = 24;
		$p1->speak('Zhang San')
		    echo $p1->name;
    ?>

(point) is a splice

9. Interaction between PHP and the preceding paragraph

PHP receives front-end data

	$_GET['Parameter name']
	$_POST['Parameter name']
	Chinese solution for request parameters
	header('Content-type:html;charset=utf-8');

10. Database

Concept: database is a warehouse organized, stored and managed according to data structure.

Warehouse: Warehouse

Table: a warehouse is divided into many parts. I really want to class

Fields: properties like classes

	int ---> Integer type
	varchar ---> String type
	blob ---> Binary type
	date ---> Date type

10.1 common databases

Relational database:

oracle , mysql , SQLServer , DB2 , sybase

Non relational database

Redis , HBAse , CouchDB , MongoDB

Use of MySQL

Utility: phpstudy. Click mySQL manager and select mySQL front to enter the SQL editor

Open a library: use mydb

Create table:

	create table students(
	  sex char(4) not null;
	  name varchar(8) not null;
)

• Add a record

	insert into book(username,userpass) value('Zhang San'，'123)

• delete

	delete from book where username='Zhang San'

• check

	select * from book where username='Zhang' and usersex='male'

• change

	update book set usersex='female' where username='Zhang San'

10.2 PHP link Mysql

Connect to database: mysqli_connect();

Syntax: mysqli_conncet(servername,username,password,dbname)

Parameters:

• servername: Specifies the name of the server to be connected: the default is' localhost:3306 ';
• Password: specify the password used for login;
• dbname: indicates the database name