Ultimate PHP & MySQL Web Development Course & OOP Coding

Learn about the basic format of a PHP file and how to utilise basic features.

The echo() function outputs one or more strings.

Note: The echo() function is not actually a function, so you are not required to use parentheses with it. However, if you want to pass more than one parameter to echo(), using parentheses will generate a parse error.

In computer programming, a comment is a programmer-readable explanation or annotation in the source code of a computer program. They are added with the purpose of making the source code easier for humans to understand, and are generally ignored by compilers and interpreters.

In computer programming, a variable or scalar is a storage location paired with an associated symbolic name, which contains some known or unknown quantity of information referred to as a value.

The data types that hold numeric values are: byte , short , int , long , float and double . The difference between them is the size and precision of the value they contain. Multiple characters or 'strings' (eg words and sentences) are also supported in Java through the use of String .

A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume).

Rules for PHP variables:

• A variable starts with the $ sign, followed by the name of the variable

• A variable name must start with a letter or the underscore character

• A variable name cannot start with a number

• A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )

• Variable names are case-sensitive ($age and $AGE are two different variables)

In programming, a constant is a value that never changes. The other type of values that programs use is variables, symbols that can represent different values throughout the course of a program.

In computer science, an array data structure, or simply an array, is a data structure consisting of a collection of elements, each identified by at least one array index or key. An array is stored such that the position of each element can be computed from its index tuple by a mathematical formula.

In computer science, an associative array, symbol table, dictionary, or collection of tuples is an abstract data type that maps a unique string to an instance of an object.

A multidimensional array is an array containing one or more arrays. PHP understands multidimensional arrays that are two, three, four, five, or more levels deep. However, arrays more than three levels deep are hard to manage for most people.

The if/else statement executes a block of code if a specified condition is true. If the condition is false, another block of code can be executed. The if/else statement is a part of PHP's "Conditional" Statements, which are used to perform different actions based on different conditions.

The if/else statement executes a block of code if a specified condition is true. If the condition is false, another block of code can be executed. The if/else statement is a part of PHP's "Conditional" Statements, which are used to perform different actions based on different conditions.

The elseif statement is only executed if the preceding if expression and any preceding elseif expressions evaluated to FALSE, and the current elseif expression evaluated to TRUE .

In computer programming languages, a switch statement is a type of selection control mechanism used to allow the value of a variable or expression to change the control flow of program execution via search and map.

In most computer programming languages, a while loop is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition. The while loop can be thought of as a repeating if statement.

In most computer programming languages, a do while loop is a control flow statement that executes a block of code at least once, and then repeatedly executes the block, or not, depending on a given boolean condition at the end of the block.

The for statement is used to iterate over the elements of a sequence. It's traditionally used when you have a piece of code which you want to repeat n number of time. The for loop is often distinguished by an explicit loop counter or loop variable.

Looping in a programming language is a way to execute a statement or a set of statements multiple numbers of times depending on the result of a condition to be evaluated. The resulting condition should be true to execute statements within loops. The foreach loop is used to iterate over the elements of the collection.

The break statement terminates the current loop, switch, or label statement and transfers program control to the statement following the terminated statement.

The continue statement is used inside loops. When a continue statement is encountered inside a loop, control jumps to the beginning of the loop for next iteration, skipping the execution of statements inside the body of loop for the current iteration.

A function is a block of organised, reusable code that is used to perform a single, related action. Functions provide better modularity for your application and a high degree of code reusing. You have already seen various functions like printf() and main().

Passing arguments by reference and by value. When you pass an argument by reference, you pass a pointer to the value in memory. The function operates on the argument. When a function changes the value of an argument passed by reference, the original value changes.

Passing by reference means the called functions' parameter will be the same as the callers' passed argument (not the value, but the identity - the variable itself).Pass by value means the called functions' parameter will be a copy of the callers' passed argument.

A default argument is a value provided in a function declaration that is automatically assigned by the compiler if the caller of the function doesn't provide a value for the argument with a default value.

A return is a value that a function returns to the calling script or function when it completes its task. A return value can be any one of the four variable types: handle, integer, object, or string.

PHP supports the concept of variable functions. This means that if a variable name has parentheses appended to it, PHP will look for a function with the same name as whatever the variable evaluates to, and will attempt to execute it. Among other things, this can be used to implement callbacks, function tables, and so forth.

Scope refers to the visibility of variables. In other words, which parts of your program can see or use it. Normally, every variable has a global scope. Once defined, every part of your program can access a variable. It is very useful to be able to limit a variable's scope to a single function.

Learn about implementing simple HTML form with a PHP backend

Both GET and POST create an array (e.g. array( key1 => value1, key2 => value2, key3 => value3, ...)). This array holds key/value pairs, where keys are the names of the form controls and values are the input data from the user.

Both GET and POST are treated as $_GET and $_POST. These are superglobals, which means that they are always accessible, regardless of scope - and you can access them from any function, class or file without having to do anything special.

$_GET is an array of variables passed to the current script via the URL parameters.

$_POST is an array of variables passed to the current script via the HTTP POST method.

The $_SERVER["PHP_SELF"] variable can be used by hackers!

If PHP_SELF is used in your page then a user can enter a slash (/) and then some Cross Site Scripting (XSS) commands to execute.

The first thing we will do is to pass all variables through PHP's htmlspecialchars() function.

Some fields cannot be empty, lets cover this in this video.

If you are having problems with your PHP web application and need to display all the errors and warnings, you are in the right place. In this tutorial, we will explain all the different ways to enable PHP errors and warnings.

If the name syntax is not valid, then lets show an error message:

If the email address syntax is not valid, then lets show an error message:

If the URL address syntax is not valid, then lets show an error message:

To show the values in the input fields after the user hits the submit button, we add a little PHP script inside the value attribute.

The readfile() function reads a file and writes it to the output buffer.

A better method to open files is with the fopen() function. This function gives you more options than the readfile() function.

The fread() function reads from an open file.

The first parameter of fread() contains the name of the file to read from and the second parameter specifies the maximum number of bytes to read.

The fclose() function is used to close an open file.

The fgets() function is used to read a single line from a file.

The feof() function checks if the "end-of-file" (EOF) has been reached.

The feof() function is useful for looping through data of unknown length.

The fgetc() function is used to read a single character from a file.

The fwrite() function is used to write to a file.

The first parameter of fwrite() contains the name of the file to write to and the second parameter is the string to be written.

First, ensure that PHP is configured to allow file uploads.

In your "php.ini" file, search for the file_uploads directive, and set it to On:

Next, let's create an HTML form that allow users to choose the image file they want to upload.

Let's create the PHP backend for uploading files.

Now lets check if the file exists and prevent replacing the file.

Now, we want to check the size of the file.

Now we will restrict the type of images acceptable.

The MySQLi is an extension to work with MySQL version 4.1.13 or newer. MySQLi is introduced with PHP Version 5.0 and is a replacement for the mysql functions, with object-oriented and procedural versions. ... PDO (PHP Data Objects) is a general database abstraction layer with support for MySQL among many other databases.

Let's create a database and table for our PHP web application.

Database connection. A Database connection is a facility in computer science that allows client software to talk to database server software, whether on the same machine or not. ... The Connection String is composed of a set of key/value pairs as dictated by the data access interface and data provider being used.

The SELECT statement is used to select data from a database.

The data returned is stored in a result table, called the result-set.

The WHERE clause is used to filter records.

The WHERE clause is used to extract only those records that fulfill a specified condition.

The LIKE operator is used in a WHERE clause to search for a specified pattern in a column.

There are two wildcards often used in conjunction with the LIKE operator:

• % - The percent sign represents zero, one, or multiple characters

• _ - The underscore represents a single character

The ORDER BY keyword is used to sort the result-set in ascending or descending order.

The ORDER BY keyword sorts the records in ascending order by default. To sort the records in descending order, use the DESC keyword.

A JOIN clause is used to combine rows from two or more tables, based on a related column between them.

The INSERT INTO statement is used to insert new records in a table.

Get the primary key/id of the last inserted row.

If you want to insert more rows than that, you should consider using multiple INSERT statements, BULK INSERT or a derived table.

The UPDATE statement is used to modify the existing records in a table.

The DELETE statement is used to delete existing records in a table.

The TRUNCATE TABLE statement is used to delete the data inside a table, but not the table itself.

The DROP TABLE statement is used to drop an existing table in a database.

The SQL SELECT LIMIT statement is used to retrieve records from one or more tables in a database and limit the number of records returned based on a limit value.

The CREATE TABLE statement is used to create a new table in a database.

In this tutorial you will learn how to create a duplicate copy of an existing table.

The ALTER TABLE statement is used to add, delete, or modify columns in an existing table.

The ALTER TABLE statement is also used to add and drop various constraints on an existing table.

The SQL CREATE DATABASE statement is used to create a new SQL database.

DROP DATABASE drops all tables in the database and deletes the database.

In a nutshell, with prepared statements malicious code introduced via user input will not be executed! In SQL Server, using a prepared statement is definitely injection-proof because the input parameters don't form the query. It means that the executed query is not a dynamic query.

XML stands for eXtensible Markup Language. XML is a markup language much like HTML. XML was designed to store and transport data. XML was designed to be self-descriptive. XML is a W3C Recommendation.

SimpleXML is an extension that allows us to easily manipulate and get XML data.

SimpleXML provides an easy way of getting an element's name, attributes and textual content if you know the XML document's structure or layout.

SimpleXML turns an XML document into a data structure you can iterate through like a collection of arrays and objects.

The PHP simplexml_load_string() function is used to read XML data from a string.

The PHP simplexml_load_file() function is used to read XML data from a file.

Get the Value of an Element

The text value of an element node is stored in a child node. This node is called a text node. To retrieve the text value of an element, you must retrieve the value of the elements' text node.

When there are multiple nodes on the same level we can access specific nodes.

We can loop over all of the nodes in an XML file to aid in the traversal of XML nodes.

In the DOM, attributes are nodes. Unlike element nodes, attribute nodes have text values. The way to get the value of an attribute, is to get its text value.

Expat is a stream-oriented XML 1.0 parser library, written in C. As one of the first available open-source XML parsers, Expat has found a place in many open-source projects. Such projects include the Apache HTTP Server, Mozilla, Perl, Python and PHP. It is also bound in many other languages.

The built-in XML Expat Parser makes it possible to process XML documents in PHP.

The built-in DOM parser makes it possible to process XML documents in PHP.

Looping means traversing through or traveling across the node tree.

Ajax is short for Asynchronous JavaScript and XML, which refers to a set of web development techniques rather than an actual programming language. Ajax however, is widely used in client-side programming (e.g. JavaScript) to allow for data to be sent and received to and from a database / server.

AJAX is used to create more interactive applications.

Let's implement the HTML/JavaScript frontend.

AJAX is used to create more interactive applications.

Let's implement the PHP backend.

AJAX can be used for interactive communication with a database.

There are two main types of email you can send and receive: plain text emails(these are exactly what they sound like -- any email that contains just plain old text with no formatting) and HTML emails, which are formatted and styled using HTML and inline CSS.

Plain text emails are easy to spot -- they are just simple text, no styling, all the same size.

There are two main types of email you can send and receive: plain text emails(these are exactly what they sound like -- any email that contains just plain old text with no formatting) and HTML emails, which are formatted and styled using HTML and inline CSS.

HTML emails are easy to spot -- most of the styled, multimedia marketing emails in your inbox are HTML emails.

The mail() function doesn’t support attachment or HTML mail by default. You need to use different headers and MIME mail parts to make this possible.

PHPMailer is a code library to send emails safely and easily via PHP code from a web server. Sending emails directly by PHP code requires a high-level familiarity to SMTP standard protocol and related issues and vulnerabilities about Email injection for spamming.

There are two main types of email you can send and receive: plain text emails(these are exactly what they sound like -- any email that contains just plain old text with no formatting) and HTML emails, which are formatted and styled using HTML and inline CSS.

Plain text emails are easy to spot -- they are just simple text, no styling, all the same size.

There are two main types of email you can send and receive: plain text emails(these are exactly what they sound like -- any email that contains just plain old text with no formatting) and HTML emails, which are formatted and styled using HTML and inline CSS.

HTML emails are easy to spot -- most of the styled, multimedia marketing emails in your inbox are HTML emails.

The mail() function doesn’t support attachment or HTML mail by default. It is better to use PHPMailer.