BackEnd Technologies
BACK END TECHNOLOGY
1.PHP
Incorporating PHP Within HTML By default, PHP documents end with the extension .php. When a web server encoun‐ ters this extension in a requested file, it automatically passes it to the PHP processor. Of course, web servers are highly configurable, and some web developers choose to 35 force files ending with .htm or .html to also get parsed by the PHP processor, usually because they want to hide the fact that they are using PHP.
Your PHP program is responsible for passing back a clean file suitable for display in a web browser. At its very simplest, a PHP document will output only HTML. To prove this, you can take any normal HTML document such as an index.html file and save it as index.php, and it will display identically to the original. To trigger the PHP commands, you need to learn a new tag. Here is the first part: A small PHP “Hello World” program might look like Example 3-1. Example 3-1. Invoking PHP The way you use this tag is quite flexible. Some programmers open the tag at the start of a document and close it right at the end, outputting any HTML directly from PHP commands. Others, however, choose to insert only the smallest possible fragments of PHP within these tags wherever dynamic scripting is required, leaving the rest of the document in standard HTML. The latter type of programmer generally argues that their style of coding results in faster code, while the former say that the speed increase is so minimal that it doesn’t justify the additional complexity of dropping in and out of PHP many times in a sin‐ gle document. As you learn more, you will surely discover your preferred style of PHP development, but for the sake of making the examples in this book easier to follow, I have adopted the approach of keeping the number of transfers between PHP and HTML to a mini‐ mum—generally only once or twice in a document. By the way, there is a slight variation to the PHP syntax. If you browse the Internet for PHP examples, you may also encounter code where the opening and closing syntax.
Variables
There’s a simple metaphor that will help you understand what PHP variables are all about. Just think of them as little (or big) matchboxes! That’s right—matchboxes that you’ve painted over and written names on. String variables Imagine you have a matchbox on which you have written the word username. You then write Fred Smith on a piece of paper and place it into the box (see Figure 3-2). Well, that’s the same process as assigning a string value to a variable, like this: $username = "Fred Smith"; Figure 3-2. You can think of variables as matchboxes containing items The quotation marks indicate that “Fred Smith” is a string of characters. You must enclose each string in either quotation marks or apostrophes (single quotes), although there is a subtle difference between the two types of quote, which is explained later. When you want to see what’s in the box, you open it, take the piece of paper out, and read it. In PHP, doing so looks like this: echo $username; Or you can assign it to another variable (photocopy the paper and place the copy in another matchbox), like this: $current_user = $username;
Introduction to MySQL
With well over 10 million installations, MySQL is probably the most popular database management system for web servers. Developed in the mid-1990s, it’s now a mature technology that powers many of today’s most-visited Internet destinations. One reason for its success must be the fact that, like PHP, it’s free to use. But it’s also extremely powerful and exceptionally fast—it can run on even the most basic of hardware, and it hardly puts a dent in system resources. MySQL is also highly scalable, which means that it can grow with your website (for the latest benchmarks, see http://mysql.com/why-mysql/benchmarks).
MySQL Basics
A database is a structured collection of records or data stored in a computer system and organized in such a way that it can be quickly searched and information can be rapidly retrieved. The SQL in MySQL stands for Structured Query Language. This language is loosely based on English and also used in other databases such as Oracle and Microsoft SQL Server. It is designed to allow simple requests from a database via commands such as SELECT title FROM publications WHERE author = 'Charles Dickens'; A MySQL database contains one or more tables, each of which contains records or rows. Within these rows are various columns or fields that contain the data itself. Table 8-1 shows the contents of an example database of five publications detailing the author, title, type, and year of publication.
Create a connect.php file for basic database connection use that default code as below
1.PHP
Incorporating PHP Within HTML By default, PHP documents end with the extension .php. When a web server encoun‐ ters this extension in a requested file, it automatically passes it to the PHP processor. Of course, web servers are highly configurable, and some web developers choose to 35 force files ending with .htm or .html to also get parsed by the PHP processor, usually because they want to hide the fact that they are using PHP.
Your PHP program is responsible for passing back a clean file suitable for display in a web browser. At its very simplest, a PHP document will output only HTML. To prove this, you can take any normal HTML document such as an index.html file and save it as index.php, and it will display identically to the original. To trigger the PHP commands, you need to learn a new tag. Here is the first part: A small PHP “Hello World” program might look like Example 3-1. Example 3-1. Invoking PHP The way you use this tag is quite flexible. Some programmers open the tag at the start of a document and close it right at the end, outputting any HTML directly from PHP commands. Others, however, choose to insert only the smallest possible fragments of PHP within these tags wherever dynamic scripting is required, leaving the rest of the document in standard HTML. The latter type of programmer generally argues that their style of coding results in faster code, while the former say that the speed increase is so minimal that it doesn’t justify the additional complexity of dropping in and out of PHP many times in a sin‐ gle document. As you learn more, you will surely discover your preferred style of PHP development, but for the sake of making the examples in this book easier to follow, I have adopted the approach of keeping the number of transfers between PHP and HTML to a mini‐ mum—generally only once or twice in a document. By the way, there is a slight variation to the PHP syntax. If you browse the Internet for PHP examples, you may also encounter code where the opening and closing syntax.
Variables
There’s a simple metaphor that will help you understand what PHP variables are all about. Just think of them as little (or big) matchboxes! That’s right—matchboxes that you’ve painted over and written names on. String variables Imagine you have a matchbox on which you have written the word username. You then write Fred Smith on a piece of paper and place it into the box (see Figure 3-2). Well, that’s the same process as assigning a string value to a variable, like this: $username = "Fred Smith"; Figure 3-2. You can think of variables as matchboxes containing items The quotation marks indicate that “Fred Smith” is a string of characters. You must enclose each string in either quotation marks or apostrophes (single quotes), although there is a subtle difference between the two types of quote, which is explained later. When you want to see what’s in the box, you open it, take the piece of paper out, and read it. In PHP, doing so looks like this: echo $username; Or you can assign it to another variable (photocopy the paper and place the copy in another matchbox), like this: $current_user = $username;
Introduction to MySQL
With well over 10 million installations, MySQL is probably the most popular database management system for web servers. Developed in the mid-1990s, it’s now a mature technology that powers many of today’s most-visited Internet destinations. One reason for its success must be the fact that, like PHP, it’s free to use. But it’s also extremely powerful and exceptionally fast—it can run on even the most basic of hardware, and it hardly puts a dent in system resources. MySQL is also highly scalable, which means that it can grow with your website (for the latest benchmarks, see http://mysql.com/why-mysql/benchmarks).
MySQL Basics
A database is a structured collection of records or data stored in a computer system and organized in such a way that it can be quickly searched and information can be rapidly retrieved. The SQL in MySQL stands for Structured Query Language. This language is loosely based on English and also used in other databases such as Oracle and Microsoft SQL Server. It is designed to allow simple requests from a database via commands such as SELECT title FROM publications WHERE author = 'Charles Dickens'; A MySQL database contains one or more tables, each of which contains records or rows. Within these rows are various columns or fields that contain the data itself. Table 8-1 shows the contents of an example database of five publications detailing the author, title, type, and year of publication.
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