add this code into your plugin file to register activation hook
// register activation hook
register_activation_hook( __FILE__, 'my_rating_plugin_activation' );
now create a function and add your table creation code into
function my_rating_plugin_activation() {
global $wpdb, $rating_table_name;
if($wpdb->get_var("SHOW TABLES LIKE \"$rating_table_name\"") != $rating_table_name) {
$wpdb->query("CREATE TABLE IF NOT EXISTS $rating_table_name (
rating_id int(11) NOT NULL AUTO_INCREMENT,
rating_postid int(11) NOT NULL,
rating_posttitle text NOT NULL,
rating_rating int(2) NOT NULL,
rating_timestamp varchar(15) NOT NULL,
rating_ip varchar(40) NOT NULL,
rating_host varchar(200) NOT NULL,
rating_username varchar(50) NOT NULL,
rating_userid int(10) NOT NULL DEFAULT '0',
comment_id int(11) NOT NULL,
PRIMARY KEY (rating_id)
) ENGINE=MyISAM");
}
}