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Using the built-in schema

From: WordPress: Creating Custom Widgets and Plugins with PHP

Video: Using the built-in schema

So WordPress is powered by a MySQL database. This database stores all the posts, all the users, all the comments, the tags, the categories--everything you see in the WordPress environment. It can be really helpful to know the structure of this in your Plugin development. You can find this all at the Codex. There is a special page dedicated just to the database description, and you can see here, there's different versions. So the database is continually changing and evolving, which means when possible you want to use the functions created specifically to access the database instead of accessing the database directly.

Using the built-in schema

So WordPress is powered by a MySQL database. This database stores all the posts, all the users, all the comments, the tags, the categories--everything you see in the WordPress environment. It can be really helpful to know the structure of this in your Plugin development. You can find this all at the Codex. There is a special page dedicated just to the database description, and you can see here, there's different versions. So the database is continually changing and evolving, which means when possible you want to use the functions created specifically to access the database instead of accessing the database directly.

If you do need to know the structure, you can download that schema at the Codex, and you can see it here. You can see we have a posts. We have a users; that's where the main data is stored. The options are stored in a separate file, and links are stored here as well. We also have some other data types that are stored. Some of the meta comments, these are basically used for custom fields, so wp_usermeta is used whenever you create a custom field for a user, just like postmeta is created as custom fields for posts.

Keep in mind that you wouldn't have to access wp_posts; you could use the wpdbpost property to get the name of that database. In case that should never change in the future, it would keep your code from breaking. If you want to look at your database directly, along with the MAMP installation, they have an install of phpMyAdmin. This will give you access to your database. You can see it listed here. Whatever name you gave it when you first start it up, you'll to see it. When you click on it, you'll be able to access the different tables, and from there you, can see the types of data that are in each table, and you're also able to go through and view what's in the fields.

You can browse the table itself, and you can also go in and run SQL on it, and do all kinds of other tests. So the built-in database stores all kinds of information that's useful when you're working in WordPress. This includes anything from users to pages to comments and links. Understanding the structure of the database might be helpful for plugin development, if you should need to access things directly. But be careful; there are many times when you can get this data and interact this data without actually having to access it directly using the built-in functions, and when that's the case, it's usually a best practice to do so.

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This video is part of

Image for WordPress: Creating Custom Widgets and Plugins with PHP
 
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  1. 1m 49s
    1. Welcome
      1m 16s
    2. Using the exercise files
      33s
  2. 23m 29s
    1. WordPress overview
      2m 32s
    2. Installing WPI for Windows
      3m 42s
    3. Installing MAMP for the Mac
      3m 25s
    4. Installing and configuring WordPress
      5m 51s
    5. Comparing WordPress 3.0 with previous versions
      2m 57s
    6. Setting up a PHP/WordPress development environment
      5m 2s
  3. 14m 47s
    1. Exploring WordPress plugins
      3m 42s
    2. Administering plugins from the WordPress admin
      5m 23s
    3. Exploring where plugins reside
      2m 51s
    4. Introduction to hooks
      2m 51s
  4. 39m 28s
    1. Creating the plugin PHP file(s)
      3m 12s
    2. More on hooks: Actions and filters
      3m 15s
    3. Installation and activation
      4m 6s
    4. Writing activation code
      3m 45s
    5. Writing an action
      5m 12s
    6. Writing a filter
      4m 15s
    7. About pluggable functions
      2m 1s
    8. Writing a pluggable function
      5m 30s
    9. Using template tags
      2m 46s
    10. Introducing shortcode
      5m 26s
  5. 26m 2s
    1. Widgets and the WordPress Widgets SubPanel
      2m 54s
    2. Comparing widgets and plugins
      1m 8s
    3. Using and customizing built-in widgets
      3m 18s
    4. Creating a new widget
      7m 21s
    5. Writing the constructor and registering widgets
      5m 20s
    6. Enabling configuration of widgets
      6m 1s
  6. 44m 59s
    1. Creating an admin interface
      5m 25s
    2. Saving data to the database
      5m 39s
    3. Securing form submission with nonces
      2m 25s
    4. Options editing post-WordPress 2.7
      4m 8s
    5. Integrating with the WordPress admin menus
      3m 34s
    6. WordPress admin dashboard API
      4m 5s
    7. Using existing options and option editing pages in WordPress
      5m 19s
    8. Using jQuery and AJAX for administration
      14m 24s
  7. 27m 13s
    1. Accessing the WordPress database
      5m 45s
    2. Using the built-in schema
      2m 21s
    3. Accessing data using $wpdb
      5m 15s
    4. Creating new tables
      7m 18s
    5. Inserting data
      6m 34s
  8. 26m 27s
    1. Introducing the Loop
      6m 22s
    2. Using WP_Query()
      3m 11s
    3. Custom filtering and sticky posts
      4m 58s
    4. Using jQuery and AJAX for posts and pages
      11m 56s
  9. 12m 9s
    1. Registering and promoting plugins
      2m 28s
    2. Creating an uninstall function
      5m 53s
    3. Backward compatibility issues
      3m 48s
  10. 15m 3s
    1. Understanding security issues
      11m 20s
    2. Internationalizing your plugin
      3m 43s
  11. 18s
    1. Goodbye
      18s

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