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PHP with MySQL Essential Training

Associative arrays


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PHP with MySQL Essential Training

with Kevin Skoglund

Video: Associative arrays

PHP has another type of array, called an associative array. And it's important for us to learn how to use both types, and to understand the difference between them. An associative array is an object-indexed collection of objects and it's very similar to what we saw for the definition of a regular array. But notice that it doesn't say that it's ordered anymore. And instead of being integer-indexed it is object-indexed, that is, they're going to be indexed by a label of some sort. Let's remember the expanding file folder metaphor that I gave you when we were talking about arrays. Associative arrays are similar, but they work more like hanging file folders. They're not in any certain order and they can be rearranged. Each of those file folders is going to have a label on it. And that's how we're going to find information.
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  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

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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

Associative arrays

PHP has another type of array, called an associative array. And it's important for us to learn how to use both types, and to understand the difference between them. An associative array is an object-indexed collection of objects and it's very similar to what we saw for the definition of a regular array. But notice that it doesn't say that it's ordered anymore. And instead of being integer-indexed it is object-indexed, that is, they're going to be indexed by a label of some sort. Let's remember the expanding file folder metaphor that I gave you when we were talking about arrays. Associative arrays are similar, but they work more like hanging file folders. They're not in any certain order and they can be rearranged. Each of those file folders is going to have a label on it. And that's how we're going to find information.

Since we won't know what order the information is in, instead we will thumb through those file folders until we find label that matches what we're looking for. Instead of saying, our phone bill is in pocket 1, and our electric bill is in pocket 2, instead we'll say, find the pocket labeled phone bill and pull out its contents. We call the label on each of these pockets the key, and the contents of what's inside the pocket the value. And the combination of the label and the value is referred to as the key value pair. So we'll always have a series of keys and values that make up our associative array.

Both an array and associative array have their uses. When the order matters to us we want to use an array. When the order is not important, we want to have the convenience of having a label that we can refer to, well then we want to use an associative array. So if we have 100 customers, we would want to store them in a ray. The order of those customers is what matters. But then the information about each customer, I would want to store in an associate of array. I don't care that the first item in the array is their first name. In fact, I don't want to have to remember the order in which the data is stored. Instead I want to be able to ask the array, give me back the information that's labelled first name, and retrieve the data that I'm looking for. So both of them are going to have their place.

Let's try one out. So for associative arrays, let's start by opening up basic.html, we'll do Save As. We'll call this assoc_arrays. Assoc is what I'm going to use for short for association. Then make sure you put .php at the end. And here, associative arrays. Alright. Now, the function that we're going to use to create these is going to be exactly the same as what we had for our regular array. We're just going to use array with the parenthesis around it.

That is an empty associative array, as well as it is a regular array. There's really not a big difference. What matters though, is what we put inside of it. So, if for example, inside this array, I put first name as a label, that's a string, an object, it's object-indexed. And I point that and I do that using the equal sign and the greater than sign. So it looks like an arrow pointing to the next data, which is the value. So the key is first name, the value is Kevin. And we can have more than one of those. We can have comma and then last name.

Again, the arrow pointing to Skoglund, and you can put your own name in there instead of mine. There we go. That is what an associative array looks like. Instead of being indexed by the position, it's going to be indexed by the key. So if I wanted to get back the first name, (SOUND) echo, then I would do it by saying variable assoc square brackets still. Still asking for the value using square brackets, and now I need to put the index in here. Still an index. Before it was an index that was a position, now it's an index that's an object, and the object is the string first name.

Has to match exactly because that's the label. I'm looking for first name with that exact capitalization with the underscore in between them. Let's just put a br tag at the end of that. And let's bring that up in a browser. Instead of just arrays let's put assoc underscore in front of it. And there we go. It brought back the first name for us. It looked it up in our array based on its label. That's what it was indexed by. And of course, if we wanted to bring up both first name and last name, we know how to do that using a pen. I'll put a space, and then I'll just copy this, paste it here and turn this into last name. Bring that up, and you'll see that it brings back both values. Now assignment works the exact same way that it did when we were working with regular arrays.

We have assoc and then first name equals Larry. That's going to assign Larry to the thing that's labeled, that's index by first name, and then let's just echo it again, so that we can see the results. You can see now it's changed it and the value is equal to Larry in there. Now numbers don't work anymore. So for example, if we were to come down here and we were to ask it for what is in position 0, and let's bring that up.

You say it comes back and says oops, undefined offset. Right, basically I don't have an index called zero. I'm looking for zero and I don't see it there. So that's not going to work. That is unless you indexed it by using numbers. Right? Any number can be there, it doesn't have to be a string. We could use a number. So, in fact, what you'll realize is that this array that we had numbers, 4, 8, 15, 16, 23, and 42 is exactly the same as if we had this associative array written out. 0 points to 4, 1 points to 8, and so on. It's the exact same thing.

Let's just bring that up in a browser. And you can see that it brought up 4 for us. It returned this value because it's indexed with this. So, in fact, there's not a lot of difference between an array and an associative array, except that we have the convenience of not putting each one of those numbers in there, when we're just concerned about the order. So, you can see that, in fact, an array, an associative array, actually have a lot in common. They're really built the same way inside PHP. It's just that when we write it in this form, we aren't providing the indexes, we're assuming that it can be derived from the position of the items.

Whereas here, we're actually specifying what each one is. And if we wanted to make this one into 20, that's perfectly valid. We can do that. We can say that the index of it would be 20. It's not two anymore, it's 20. So arrays are going to play a big part in programming. So it's important that you make sure that you understand them. If this didn't make sense at first, then watch these two movies again and make sure that you have a good foundation on what they are and how they work before we move on. After that, we'll go to the next movie where we'll look at some functions that work on arrays.

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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.
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