Shoultes.net » MySQL

Vote for Event Espresso – 2010 Plugin of the Year

Seth — Tue, 05 Oct 2010 07:11:27 +0000

Vote for Event Espresso

Event Espresso has been nominated for the prestigious “2010 Plugin of the Year Award” at WordPress Honors. Please take a few minutes to show your support for Event Espresso (and any of your other favorite plugins,) by voting.

Need a little more incentive? Each person that registers on the WordPress Honors website will be entered to win great prizes from other great WordPress theme and plugin developers.

So hurry up and cast your vote for Event Espresso and start winning prizes!

WordPress dbDelta Function Problems

Seth — Sun, 07 Mar 2010 07:43:44 +0000

For a couple of weeks I was trying to figure out why the database tables in my plugin weren’t getting updated when the plugin was installed or activated. I had recently written a function (based on this example) to create tables in my WordPress plugin. I finally narrowed it down to the dbDelta function for WordPress. After doing a few searches on Google I came across this article which explains the the dbDelta function in detail.

Come to find out I was missing a space between a ‘“‘ and a ‘(‘ as seen below.

$sql_create_table = "CREATE TABLE " . $wp_table_name . "( " . $sql . " );";

Here is how it should have looked:

$sql_create_table = "CREATE TABLE " . $wp_table_name . "  (  " . $sql . "  )  ;";

Notice the spaces highlighted in green? That was the killer. So for a while, every time I added a new field to a table in database install file. For a while I was using a function (seen below) to alter the table and add the new fields.

function add_column_if_not_exist($db, $column, $column_attr = "VARCHAR( 255 ) NULL" ){
global $wpdb;
$exists = false;
$columns = $wpdb-&gt;query("show columns from $db");
while($c = $wpdb-&gt;get_row($columns)){
if($c['Field'] == $column){
$exists = true;
break;
}
}
if(!$exists){
if (!$wpdb-&gt;query("ALTER TABLE `$db` ADD `$column`  $column_attr")){
$error = 'There was a problem adding columns to the database.';
}
}
return $error;
}

So, if you are having trouble with the dbDelta function when writing a Wrodpress plugin. Be aware of extra spaces

Here is more information about the dbDelta function and creating tables with plugins:

http://codex.wordpress.org/Creating_Tables_with_Plugins

http://wordpress.org/tags/dbdelta-1

http://hungred.com/how-to/wordpress-dbdelta-function/

http://designoplasty.com/2009/05/15/not-using-dbdelta-with-wordpress/

Function for Creating Tables with WordPress Plugins

Seth — Sun, 07 Mar 2010 07:41:23 +0000

Here is a very useful function I have written to install/update the database tables in your custom WordPress plugin. Basically I have used the examples given on the “Creating Tables with Plugins” page at WordPress.org.

In your main plugin file (ex. my_plugin.php) I define my plugin version:

define("MY_PLUGIN_VERSION", "2.16" ); //Declare the plugin version. This way we know the tables are always up to date. I usually declare this in my main plugin file.
require_once("includes/functions.php");
require_once("includes/database_install.php");
register_activation_hook(__FILE__,'my_plugin_data_tables_install');

Then in my functions.php file:

function my_plugin_run_install ($table_name, $table_version, $sql) {
		   global $wpdb;
		   $wp_table_name = $wpdb-&gt;prefix . $table_name;
		   if($wpdb-&gt;get_var("SHOW TABLES LIKE '".$table_name."'") != $table_name) {
				$sql_create_table = "CREATE TABLE " . $wp_table_name . " ( " . $sql . " ) ;";
				require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
				dbDelta($sql_create_table);
 
			//create option for table version
				$option_name = $table_name.'_tbl_version';
				$newvalue = $table_version;
				  if ( get_option($option_name) ) {
					    update_option($option_name, $newvalue);
					  } else {
					    $deprecated=' ';
					    $autoload='no';
					    add_option($option_name, $newvalue, $deprecated, $autoload);
				  }
			//create option for table name
				$option_name = $table_name.'_tbl';
				$newvalue = $wp_table_name;
				  if ( get_option($option_name) ) {
					    update_option($option_name, $newvalue);
					  } else {
					    $deprecated=' ';
					    $autoload='no';
					    add_option($option_name, $newvalue, $deprecated, $autoload);
				  }
		}
 
	// Code here with new database upgrade info/table Must change version number to work.
	$installed_ver = get_option( $table_name.'_tbl_version' );
	     if( $installed_ver != $table_version ) {
		  $sql_create_table = "CREATE TABLE " . $wp_table_name . " ( " . $sql . " ) ;";
	      require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
	      dbDelta($sql_create_table);
	      update_option( $table_name.'_tbl_version', $table_version );
	      }
	    }

Using the function is quite simple and can save a few lines of code. especially if you need to install several new tables.

Here is an example of database_install.php:

function my_plugin_data_tables_install () {
$table_version = MY_PLUGIN_VERSION; //Call the plugin version.
//Install the first table
$table_name = "my_first_plugin_tbl";
$sql = "id mediumint(9) NOT NULL AUTO_INCREMENT,
	  time bigint(11) DEFAULT '0' NOT NULL,
	  name tinytext NOT NULL,
	  text text NOT NULL,
	  url VARCHAR(100) NOT NULL,
	  UNIQUE KEY id (id)";
my_plugin_run_install  ($table_name, $table_version, $sql);
 
//Install the second table
$table_name = "my_second_plugin_tbl";
$sql = "id mediumint(9) NOT NULL AUTO_INCREMENT,
	   category_name VARCHAR(100) DEFAULT NULL,
	   category_identifier VARCHAR(45) DEFAULT NULL,
	   category_desc TEXT,
	   display_desc VARCHAR (4) DEFAULT NULL,
	  UNIQUE KEY id (id)";
my_plugin_run_install  ($table_name, $table_version, $sql);
}

I hope this helps some of the WordPress plugin authors out there.