Start learning with our library of video tutorials taught by experts. Get started

PHP with MySQL Essential Training

Using GET values


From:

PHP with MySQL Essential Training

with Kevin Skoglund

Video: Using GET values

In this movie, we'll learn how to send a value from one page to the next by using the URL query parameters. The query parameters are the part of the URL that comes after the question mark. This is typically were you send additional parameters that the page needs. The format is always the name of the parameter, an equals sign and then the value of the parameter. Often these parameters modify the behavior of the code used to generate the returned HTML. For example, somepage.php?page=2 would process the same PHP code but the content return would probably be modified. It would do something like return a second page of search results. And you can send more than one query parameter in the URL by using an ampersand between each one of these parameters.
Expand all | Collapse all
  1. 4m 8s
    1. Welcome
      1m 0s
    2. Using the exercise files
      3m 8s
  2. 15m 6s
    1. What is PHP?
      3m 52s
    2. The history of PHP
      2m 51s
    3. Why choose PHP?
      4m 10s
    4. Installation overview
      4m 13s
  3. 54m 53s
    1. Overview
      2m 33s
    2. Working with Apache Web Server
      6m 56s
    3. Changing the document root
      7m 24s
    4. Enabling PHP
      6m 16s
    5. Upgrading PHP
      3m 30s
    6. Configuring PHP
      10m 3s
    7. Installing MySQL
      5m 46s
    8. Configuring MySQL
      7m 24s
    9. Text editor
      5m 1s
  4. 31m 25s
    1. Overview
      3m 27s
    2. Installing WampServer
      5m 46s
    3. Finding the document root
      2m 24s
    4. Configuring PHP
      8m 12s
    5. Configuring MySQL
      5m 45s
    6. Text editor
      5m 51s
  5. 19m 12s
    1. Embedding PHP code on a page
      6m 43s
    2. Outputting dynamic text
      5m 55s
    3. The operational trail
      2m 27s
    4. Inserting code comments
      4m 7s
  6. 1h 18m
    1. Variables
      7m 50s
    2. Strings
      4m 38s
    3. String functions
      8m 54s
    4. Numbers part one: Integers
      6m 27s
    5. Numbers part two: Floating points
      5m 25s
    6. Arrays
      10m 0s
    7. Associative arrays
      6m 37s
    8. Array functions
      6m 33s
    9. Booleans
      3m 50s
    10. NULL and empty
      5m 15s
    11. Type juggling and casting
      8m 27s
    12. Constants
      4m 43s
  7. 27m 37s
    1. If statements
      6m 0s
    2. Else and elseif statements
      4m 16s
    3. Logical operators
      7m 30s
    4. Switch statements
      9m 51s
  8. 42m 15s
    1. While loops
      8m 41s
    2. For loops
      5m 59s
    3. Foreach loops
      8m 16s
    4. Continue
      8m 28s
    5. Break
      4m 8s
    6. Understanding array pointers
      6m 43s
  9. 37m 25s
    1. Defining functions
      8m 25s
    2. Function arguments
      5m 32s
    3. Returning values from a function
      7m 33s
    4. Multiple return values
      4m 53s
    5. Scope and global variables
      6m 2s
    6. Setting default argument values
      5m 0s
  10. 20m 18s
    1. Common problems
      3m 47s
    2. Warnings and errors
      8m 36s
    3. Debugging and troubleshooting
      7m 55s
  11. 57m 57s
    1. Links and URLs
      5m 33s
    2. Using GET values
      5m 35s
    3. Encoding GET values
      8m 41s
    4. Encoding for HTML
      9m 26s
    5. Including and requiring files
      7m 40s
    6. Modifying headers
      6m 45s
    7. Page redirection
      6m 43s
    8. Output buffering
      7m 34s
  12. 1h 3m
    1. Building forms
      7m 28s
    2. Detecting form submissions
      5m 59s
    3. Single-page form processing
      7m 57s
    4. Validating form values
      10m 40s
    5. Problems with validation logic
      9m 54s
    6. Displaying validation errors
      7m 23s
    7. Custom validation functions
      6m 28s
    8. Single-page form with validations
      7m 25s
  13. 28m 5s
    1. Working with cookies
      2m 49s
    2. Setting cookie values
      5m 55s
    3. Reading cookie values
      6m 1s
    4. Unsetting cookie values
      4m 51s
    5. Working with sessions
      8m 29s
  14. 48m 39s
    1. MySQL introduction
      6m 43s
    2. Creating a database
      7m 41s
    3. Creating a database table
      7m 42s
    4. CRUD in MySQL
      5m 48s
    5. Populating a MySQL database
      7m 32s
    6. Relational database tables
      6m 40s
    7. Populating the relational table
      6m 33s
  15. 56m 4s
    1. Database APIs in PHP
      4m 51s
    2. Connecting to MySQL with PHP
      7m 45s
    3. Retrieving data from MySQL
      8m 47s
    4. Working with retrieved data
      6m 12s
    5. Creating records with PHP
      6m 58s
    6. Updating and deleting records with PHP
      9m 6s
    7. SQL injection
      3m 5s
    8. Escaping strings for MySQL
      6m 45s
    9. Introducing prepared statements
      2m 35s
  16. 35m 58s
    1. Blueprinting the application
      7m 19s
    2. Building the CMS database
      5m 14s
    3. Establishing your work area
      4m 38s
    4. Creating and styling the first page
      4m 22s
    5. Making page assets reusable
      6m 36s
    6. Connecting the application to the database
      7m 49s
  17. 32m 49s
    1. Adding pages to the navigation subjects
      5m 58s
    2. Refactoring the navigation
      6m 7s
    3. Selecting pages from the navigation
      6m 2s
    4. Highlighting the current page
      5m 26s
    5. Moving the navigation to a function
      9m 16s
  18. 1h 45m
    1. Finding a subject in the database
      9m 48s
    2. Refactoring the page selection
      10m 52s
    3. Creating a new subject form
      6m 55s
    4. Processing form values and adding subjects
      11m 20s
    5. Passing data in the session
      9m 16s
    6. Validating form values
      9m 40s
    7. Creating an edit subject form
      8m 30s
    8. Using single-page submission
      7m 44s
    9. Deleting a subject
      9m 44s
    10. Cleaning up
      10m 37s
    11. Assignment: Pages CRUD
      4m 30s
    12. Assignment results: Pages CRUD
      6m 10s
  19. 39m 26s
    1. The public appearance
      8m 52s
    2. Using a context for conditional code
      11m 37s
    3. Adding a default subject behavior
      6m 9s
    4. The public content area
      5m 51s
    5. Protecting page visibility
      6m 57s
  20. 1h 3m
    1. User authentication overview
      4m 3s
    2. Admin CRUD
      8m 41s
    3. Encrypting passwords
      7m 26s
    4. Salting passwords
      5m 42s
    5. Adding password encryption to CMS
      11m 54s
    6. New PHP password functions
      3m 13s
    7. Creating a login system
      11m 28s
    8. Checking for authorization
      5m 48s
    9. Creating a logout page
      5m 40s
  21. 2m 4s
    1. Next steps
      2m 4s

Watch this entire course now—plus get access to every course in the library. Each course includes high-quality videos taught by expert instructors.

Become a member
Please wait...
PHP with MySQL Essential Training
14h 24m Beginner Jun 04, 2013

Viewers: in countries Watching now:

PHP is a popular, reliable programming language at the foundation of many smart, data-driven websites. This comprehensive course from Kevin Skoglund helps developers learn the basics of PHP (including variables, logical expressions, loops, and functions), understand how to connect PHP to a MySQL database, and gain experience developing a complete web application with site navigation, form validation, and a password-protected admin area. Kevin also covers the basic CRUD routines for updating a database, debugging techniques, and usable user interfaces. Along the way, he provides practical advice, offers examples of best practices, and demonstrates refactoring techniques to improve existing code.

Topics include:
  • What is PHP?
  • Installing and configuring PHP and MySQL
  • Exploring data types
  • Controlling code with logical expressions and loops
  • Using PHP's built-in functions
  • Writing custom functions
  • Building dynamic webpages
  • Working with forms and form data
  • Using cookies and sessions to store data
  • Connecting to MySQL with PHP
  • Creating and editing database records
  • Building a content management system
  • Adding user authentication
Subjects:
Developer Servers Programming Languages Web Development
Software:
MySQL PHP
Author:
Kevin Skoglund

Using GET values

In this movie, we'll learn how to send a value from one page to the next by using the URL query parameters. The query parameters are the part of the URL that comes after the question mark. This is typically were you send additional parameters that the page needs. The format is always the name of the parameter, an equals sign and then the value of the parameter. Often these parameters modify the behavior of the code used to generate the returned HTML. For example, somepage.php?page=2 would process the same PHP code but the content return would probably be modified. It would do something like return a second page of search results. And you can send more than one query parameter in the URL by using an ampersand between each one of these parameters.

You can surf around the web and see lots of examples on sites like Google and Amazon where you can see these query parameters being used. It happens all over the web. Now in PHP whenever a page request is made, PHP is automatically going to take all of those query parameters that were sent with the URL and put them into an associative array where we can access them. That array is what is called a Super global variable. We've talked about global variables before and we saw how we needed to call global on them to bring them into the local scope. Well super global's are always available in all scopes and PHP set's them for us before the page even starts processing. There are about nine super globals altogether.

And we'll be looking at several of them later in this training. But right now we're only concerned with the super global that relates to the variables passed to the page via those URL parameters. And that one is called GET. And that makes sense, because GET is the HTTP method that relates to URLs and links. And the way that we access it is with dollar sign, underscore and then all capitals GET. That's the same of the super global where the query parameters are put by PHP. Notice the undersocre that's in the begining. That's how all super globals are going to be named.

Incidentially this is why in the movie about variables I suggested that you should not name your variables with underscores at the start. It helps to make these super globals really stand out. And because it's in all capitals don't get it confused with being a constant. It is still a variable, it has that dollar sign at the beginning. It's a super global variable. Alright, so now that we know where these are stored, let's see how we access them. In the last movie, we created first page.php and we also created second page.php. And we created a link on the first page and that link sends a get request to the second page. And all of the query parameters are sent with that link. In this case we're sending id equals 2.

We're doing that right here, id equals and then the value of id, which is 2. And all of those query parameters that are sent with that link are going to be stored in the super global get. So the get super global is going to be an associative array. So let's use print r so that we can take a look at the contents of that array. So let's just go to second page, here we are. And in second page I'm going to use my pretags first because that's going to make it look nice with print r and then we'll use php print r.

And we'll use our super global GET and let's just take a look at what that value looks like. We're just inspecting it. Let's go back here. Now typing a URL in the browser bar is 100% the same as clicking on a link. We don't have to go back to first page we can just re-load this page. Or we can type the URL in directly. Both of those make GET request to our server. So let's re-load it and there it is array id equal to 2. And we know how to access values that are in the array. Before we do that, though, I just want to show you, let's take away this parameter so that there is nothing after it and let's just hit Return to load that URL.

And you see that comes back empty. You can put anything you want up here in the string to try it, 34&name=kevin, and whatever's up here just gets dropped into our associative array. So if our link sends these parameters, if that's what our link looks like then that's what will be sent to the second page. Okay, so we know how to access the values that are stored in associative arrays. I'm just going to make my little window here a little smaller so I can now see. Here we go, second page. What we want to do now is instead of doing print r, let's just comment that out. And instead, let's set id equal to $ Get and then the key that goes with it, id.

That's it. So that will now take that value that was in that associative array and assign it to the variable id. Now we can work with it. Let's just echo it for now, echo id back, let's go back and let's reload this page, I'm going to go all the way back to first page, there we are, so now I'm on first page, let's reload that... Click second page and there it is. It output the 2 for us. Now I've still got my pre tags around all of this which is why it put the 2 way out here in the middle. You could also just move this down here and that's outside the pre tag. So let's do a new block of php.

All right, so that's just a little cleaner. We'll go back and reload the page and there it is, outputting our value of 2. So let's go back to our first page. And let's say that first page sent an id of 5. Save that. We'll go back to first page, reload that page. Must reload it so that we get that new value in here. because otherwise the HTML that's here on the page is the old HTML. So we reload the page. Now I click it and it comes up with 5. So we've already made our website a lot more dynamic by allowing us to pass values between pages in these URL query parameters.

This raises an important issue though. Can a user send any value in that URL? For example, what if their value had an ampersand in it? Would it still be read correctly or would it interfere with the processing of that URL? Well there are some characters that we have to watch out for. And in the next movie we're going to look at how to encode those values to make sure that they work properly.

Find answers to the most frequently asked questions about PHP with MySQL Essential Training.


Expand all | Collapse all
Please wait...
Q: This course was revised on 6/4/2013. What changed?
A: The old version of this course was 6 years old and it was time for a complete revision, using PHP 5.4. (The tutorials will work with any version of PHP and covers any differences you might encounter). The author has also added updated installation instructions for Mac OS X Mountain Lion and Windows 8. The topics and end project are the same, but the code is slightly different. It also addresses frequently asked questions from the previous version.
Share a link to this course
Please wait... Please wait...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.
Upgrade now


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

join now

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed PHP with MySQL Essential Training.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Welcome to the redesigned course page.

We’ve moved some things around, and now you can



Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked