为WordPress主题或插件创建和使用自己的表

//Active
register_activation_hook(__FILE__,'coolwp_message_active');
/**
*return:Creat my table when my plugin be activated.
*parameter:none
*@author:Suifengtec suoling.net
*/
function coolwp_message_active() {
	global $wpdb;
	$table_name = CWP_PLUGIN_PM_TABLE;
	if($wpdb->get_var("show tables like '$table_name'") != $table_name){
		$sql = 'CREATE TABLE IF NOT EXISTS `'.$table_name.'` (
			`id` int(11) NOT NULL auto_increment,
			`from_id` text default NULL,
			`from_time` datetime default NULL,
			`to_id` varchar(200) default NULL,
			`viewed` varchar(10) default NULL,
			`subject` varchar(200) default NULL,
			`content` text,
			UNIQUE KEY `id` (`id`)
			) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;';
require_once(ABSPATH . 'wp-admin/upgrade-functions.php');
dbDelta($sql);
}
}

//Deactive
register_deactivation_hook( __FILE__, 'coolwp_message_deactive' );
/**
*return:Delete my table when my plugin be deactivated.
*parameter:none
*@author:Suifengtec suoling.net
*/
function coolwp_message_deactive() {
	global $wpdb;
	$table_name = CWP_PLUGIN_PM_TABLE;
	if($wpdb->get_var("show tables like '$table_name'")== $table_name){
		$sql = 'DROP TABLE  `'.$table_name.'`';
		$wpdb->query($sql);
	}
}

<?php if(current_user_can( 'manage_options' )): ?>
<input type="submit" name="alp_edit" value="确定" class="button-primary" /> |
<?php endif; ?>

if($_POST['cwp_pm_edit']){
	$sql = 'update '.$table_name.' set  content="'.$data['content'].'" ,subject = "'.$data['subject'].'" where id = '.$data['id'];
	if($wpdb->query($sql)){
		coolwp_alp_message_LastUrl('update');
	}else{
		cwp_alp_message_sql_error('update');
	};
}//edit

/**  
*return: Redirect.  
*parameter:the action name.  
*@author:Suifengtec suoling.net  
*/  
function coolwp_alp_message_LastUrl($str){
/*
php.ini中有一段话：  
; Output buffering allows you to send header lines (including cookies) even  
; after you send body content, at the price of slowing PHP's output layer a  
; bit.  You can enable output buffering during runtime by calling the output  
; buffering functions.  You can also enable output buffering for all files by  
; setting this directive to On.  If you wish to limit the size of the buffer  
; to a certain size - you can use a maximum number of bytes instead of 'On', as  
; a value for this directive (e.g., output_buffering=4096).  
output_buffering = Off  
,我调试用的php环境的output_buffering是关闭的，output_buffering的作用是缓冲输出，如果是output_buffering=XXXX（比如是4096，那么，缓冲区大小是4096b，），那么就需要ob_end_clean();这一句了。  
ob_end_flush()或者ob_end_clean()的作用是终止缓冲；  
ob_flush()的作用是将缓冲输出出去，但是不会终止缓冲，所以在flush()之前使用；  
如不想使用ob_end_clean()、ob_end_flush()、ob_flush()，就需要把php.ini里的output_buffering设得足够小，例如0，也可以关闭了，也就是output_buffering = Off。  
注意：  
ob_flush()和flush()是有区别的：前者是把数据从PHP的缓冲中释放出来，后者是把不在缓冲中的或者说是被释放出来的数据发送到浏览器。所以当缓冲存在的时候，我们必须ob_flush()和flush()同时使用。  
当然flush()也并不是不可或缺的，你如果决定在有数据输出时，马上输出到浏览器的话，可以上去flush();  
当你把output_buffering设为0或者Off的时候，连ob_flush()和ob_end_clean()都不需要了.  
OVER  
by Suifengtec 2014.02.23 Suoling.net  
*/  
	ob_end_clean();   //清空（擦除）缓冲区并关闭输出缓冲。此函数丢弃最顶层输出缓冲区的内容并关闭这个缓冲区。如果想要进一步处理缓冲区的内容，必须在ob_end_clean()之前调用ob_get_contents()，因为当调用ob_end_clean()时缓冲区内容将被丢弃。
	if('save'==$str){   
		header("Location:".$_SERVER ['HTTP_REFERER' ].'#send');   
	}elseif('delete'==$str||'update'==$str){   
		header("Location:".$_SERVER ['HTTP_REFERER' ].'#list');   
	}
	//正确下面两个函数的顺序是： 先ob_flush, 然后flush
	ob_flush();   //取出PHP buffering中的数据,放入server buffering
	flush();   // 取出Server buffering的数据,放入browser buffering，简单说，就是刷新输出缓冲
}

//Throw a sql error info.
function cwp_alp_message_sql_error($str){
if('save'==$str)
add_action( 'admin_notices', 'cwp_alp_message_sql_save_error');
 
if('update'==$str)
add_action( 'admin_notices', 'cwp_alp_message_sql_update_error');
 
if('view'==$str)
add_action( 'admin_notices', 'cwp_alp_message_sql_view_error');
 
if('delete'==$str)
add_action( 'admin_notices', 'cwp_alp_message_sql_delete_error');
}

/**
*return: Correct sql query
*parameter:none
*@author:Suifengtec suoling.net
*/
function cwp_alp_message_received(){
	$table_name =CWP_PLUGIN_PM_TABLE;//已被定义的表名常量：define('CWP_PLUGIN_PM_TABLE',$table_prefix .'cwp_XXX');
	$usr_name=cwp_get_current_user();
	return 'select * from  '.$table_name.' '.'where to_id = "'.$usr_name.'"'.' AND viewed = "0"';
}

/**
*return: The amount of message I received
*parameter:none
*@author:Suifengtec suoling.net
*/
function cwp_alp_num_of_message_i_has_received(){
	global $wpdb;
	$table_name =CWP_PLUGIN_PM_TABLE;//还是表
	$sql=cwp_alp_message_received();//就是上面定义的查询语句
	$info = $wpdb->get_results($sql);
	return count($info);
}