WordPress建立数据表函数dbDelta与maybe_create_table对比

WordPress插件开发或者主题高级功能定制过程中，常常需要新建数据表以操作数据库并与WP默认的表区分开来，那么需要用到dbDelta与maybe_create_table这两种函数。它们之间有一定的区别，现比较如下：

1.用法对比

dbDelta($queries，$execute = true)

参数：

$queries

为SQL查询语句

$execute

使用dbDelta创建数据表最好先判断是否存在该表

示例：

global $wpdb;     $table_name = $wpdb->prefix . 'tin_meta';        if( $wpdb->get_var("SHOW TABLES LIKE '$table_name'") != $table_name ) :    		$sql = " CREATE TABLE `$table_name` ( 			`meta_id` int NOT NULL AUTO_INCREMENT,  			PRIMARY KEY(meta_id), 			`user_id` int, 			`meta_key` tinytext, 			`meta_value` longtext 		) ENGINE = MyISAM CHARSET=utf8;"; 			require_once(ABSPATH . 'wp-admin/includes/upgrade.php');    			dbDelta($sql);        endif;

global $wpdb; $table_name = $wpdb->prefix . 'tin_meta'; if( $wpdb->get_var("SHOW TABLES LIKE '$table_name'") != $table_name ) : $sql = " CREATE TABLE `$table_name` ( `meta_id` int NOT NULL AUTO_INCREMENT, PRIMARY KEY(meta_id), `user_id` int, `meta_key` tinytext, `meta_value` longtext ) ENGINE = MyISAM CHARSET=utf8;"; require_once(ABSPATH . 'wp-admin/includes/upgrade.php'); dbDelta($sql); endif;

maybe_create_table( string $table_name, string $create_ddl)

参数：

$table_name

要创建的数据表名

$create_ddl

SQL语句.

示例：

global $wpdb; 		include_once(ABSPATH.'/wp-admin/upgrade-functions.php'); 		include_once(ABSPATH.'/wp-admin/includes/upgrade.php'); 		$prefix = $wpdb->prefix; 		$tpay_download = $prefix.'tpay_download'; 		$create_tpay_download_sql = "CREATE TABLE $tpay_download (tpay_id int(11) NOT NULL auto_increment,tpay_num int(11) NOT NULL,tpay_title varchar(100) NOT NULL,tpay_post int(11) NOT NULL,tpay_price double(10,2) NOT NULL,tpay_url varchar(32) NOT NULL,tpay_user_id int(11) NOT NULL,tpay_time datetime NOT NULL,tpay_data text NOT NULL ,tpay_success int(11) NOT NULL,tpay_author int(11) NOT NULL,PRIMARY KEY (tpay_id)) $table_charset;"; 		maybe_create_table($tpay_download,$create_tpay_download_sql);

global $wpdb; include_once(ABSPATH.'/wp-admin/upgrade-functions.php'); include_once(ABSPATH.'/wp-admin/includes/upgrade.php'); $prefix = $wpdb->prefix; $tpay_download = $prefix.'tpay_download'; $create_tpay_download_sql = "CREATE TABLE $tpay_download (tpay_id int(11) NOT NULL auto_increment,tpay_num int(11) NOT NULL,tpay_title varchar(100) NOT NULL,tpay_post int(11) NOT NULL,tpay_price double(10,2) NOT NULL,tpay_url varchar(32) NOT NULL,tpay_user_id int(11) NOT NULL,tpay_time datetime NOT NULL,tpay_data text NOT NULL ,tpay_success int(11) NOT NULL,tpay_author int(11) NOT NULL,PRIMARY KEY (tpay_id)) $table_charset;"; maybe_create_table($tpay_download,$create_tpay_download_sql);

使用maybe_create_table会判断数据表是否存在，存在则不创建数据表