Mini course in PHP (Part 11) - Includes

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Hello all good people?

As promised, we will begin to make a simple news. With administration and all. Below is the scope of how our system will:

1. Administration
   1. The login page;
   2. User registration / Editing / removal;
   3. Registration categories of news / Editing / Removal;
   4. Register for news / Editing / Removal;
2. Visual part
   1. List of Categories on the menu;
   2. List of news (with or without a category filter);
   3. Form research news;
   4. Top 10 news;
   5. Send news by e-mail to friend;

But remember that we still have many things to learn about the PHP language. Decided to teach the rest by doing some simple systems, so that learning is more dynamic and that what is learned is seen in practice.

Before we start our system, we have some very important things to learn. They are:

1. Includes;

2. Basic Commands Mysql;

3. Commands for working with PHP Mysql.

INCLUDE

As its name suggests, is to include a command that includes the contents of another file where it is called. It's like you copied the code from the file and sticks where you want to use.
See how we use the include in our system of news: In order to join our administration needs to be done login. However, each page needs to be tested to see if there is someone logged and therefore allowed to see the page. Because we have the assurance that no one without a password to access our system. Then we would have an IF at the beginning of each page. The IF would be something like 'If someone has logged in, then show the page. Otherwise return to the login page. " Right? IF not to copy and paste this on ALL pages, we will create a file that contains this and IF we run INCLUDE calling this file on each page of the administration. It became clear this idea?

What is the point of using the INCLUDE? Well, imagine that your administration has 20 pages. And his rule to establish whether there is someone logged change. Oh you'll have to change the 20 pages containing this IF. Using INCLUDE this problem ... just because all the 20 pages that use the IF is written in the file that will be included.

We use an INCLUDE the following:

The file path is the folder and filename that will be included, for example: "includes / validausuario.php. To include a file that is a folder below, you will use ".." to exit the folder where your file is running. For example: ".. / includes / validausuario.php. And so on ... if you want to include a file that is three levels below you use "../../.. / includes / validausuario.php"

Check this out in practice. Consider the file a.php as follows:

And consider the file b.php as follows:

Understanding: The file b.php is calling (with the include command) a.php file. If we run the file b.php we have the following output:

But why? Because ALL the contents of the file was included in a.php b.php.

It was clear?

IMPORTANT

If the include file does not find the requested file .. it WILL NOT GIVE ERROR ... the script will proceed as normal. So in many cases, instead of using the include command () is more advisable to use the command REQUIRE, because if the file is not found the script does not continue running. The PHP parser will give error.

To learn more about include or require access to documentation on php.net: http://br2.php.net/manual/pt_BR/function.include.php

This example that was used is available in: http://www.marcelosabadini.com.br/mini-curso/include/

How Mysql is a very extensive, I will post specific to it. I'll post over the weekend.

Meanwhile, read the documentation from php.net as it is very important. Make some example ... this may even be that I .. And create another example for you to practice.

I hope I was clear enough. If you have any questions or realized that I did not say something important, please comment on the POST.

A big hug and until next time.