add_option( string $option, mixed $value = '', string $deprecated = '', string|bool $autoload = 'yes' )

添加新选项。
Adds a new option.

说明（Description）

不需要序列化值。如果需要序列化该值，则在将其插入数据库之前将对其进行序列化。请记住，资源不能序列化或作为选项添加。

可以创建不带值的选项，然后稍后更新这些值。现有选项将不会更新，并执行检查以确保您没有添加受保护的WordPress选项。应注意不要将选项命名为与受保护选项相同的选项。

参数（Parameters）

返回（Return）

源码（Source）

/**
 * Add a new option.
 *
 * You do not need to serialize values. If the value needs to be serialized, then
 * it will be serialized before it is inserted into the database. Remember,
 * resources can not be serialized or added as an option.
 *
 * You can create options without values and then update the values later.
 * Existing options will not be updated and checks are performed to ensure that you
 * aren't adding a protected WordPress option. Care should be taken to not name
 * options the same as the ones which are protected.
 *
 * @since 1.0.0
 *
 * @global wpdb $wpdb
 *
 * @param string         $option      Name of option to add. Expected to not be SQL-escaped.
 * @param mixed          $value       Optional. Option value. Must be serializable if non-scalar. Expected to not be SQL-escaped.
 * @param string         $deprecated  Optional. Description. Not used anymore.
 * @param string|bool    $autoload    Optional. Whether to load the option when WordPress starts up.
 *                                    Default is enabled. Accepts 'no' to disable for legacy reasons.
 * @return bool False if option was not added and true if option was added.
 */
function add_option( $option, $value = '', $deprecated = '', $autoload = 'yes' ) {
	global $wpdb;

	if ( !empty( $deprecated ) )
		_deprecated_argument( __FUNCTION__, '2.3' );

	$option = trim($option);
	if ( empty($option) )
		return false;

	wp_protect_special_option( $option );

	if ( is_object($value) )
		$value = clone $value;

	$value = sanitize_option( $option, $value );

	// Make sure the option doesn't already exist. We can check the 'notoptions' cache before we ask for a db query
	$notoptions = wp_cache_get( 'notoptions', 'options' );
	if ( !is_array( $notoptions ) || !isset( $notoptions[$option] ) )
		/** This filter is documented in wp-includes/option.php */
		if ( apply_filters( 'default_option_' . $option, false ) !== get_option( $option ) )
			return false;

	$serialized_value = maybe_serialize( $value );
	$autoload = ( 'no' === $autoload || false === $autoload ) ? 'no' : 'yes';

	/**
	 * Fires before an option is added.
	 *
	 * @since 2.9.0
	 *
	 * @param string $option Name of the option to add.
	 * @param mixed  $value  Value of the option.
	 */
	do_action( 'add_option', $option, $value );

	$result = $wpdb->query( $wpdb->prepare( "INSERT INTO `$wpdb->options` (`option_name`, `option_value`, `autoload`) VALUES (%s, %s, %s) ON DUPLICATE KEY UPDATE `option_name` = VALUES(`option_name`), `option_value` = VALUES(`option_value`), `autoload` = VALUES(`autoload`)", $option, $serialized_value, $autoload ) );
	if ( ! $result )
		return false;

	if ( ! defined( 'WP_INSTALLING' ) ) {
		if ( 'yes' == $autoload ) {
			$alloptions = wp_load_alloptions();
			$alloptions[ $option ] = $serialized_value;
			wp_cache_set( 'alloptions', $alloptions, 'options' );
		} else {
			wp_cache_set( $option, $serialized_value, 'options' );
		}
	}

	// This option exists now
	$notoptions = wp_cache_get( 'notoptions', 'options' ); // yes, again... we need it to be fresh
	if ( is_array( $notoptions ) && isset( $notoptions[$option] ) ) {
		unset( $notoptions[$option] );
		wp_cache_set( 'notoptions', $notoptions, 'options' );
	}

	/**
	 * Fires after a specific option has been added.
	 *
	 * The dynamic portion of the hook name, `$option`, refers to the option name.
	 *
	 * @since 2.5.0 As "add_option_{$name}"
	 * @since 3.0.0
	 *
	 * @param string $option Name of the option to add.
	 * @param mixed  $value  Value of the option.
	 */
	do_action( "add_option_{$option}", $option, $value );

	/**
	 * Fires after an option has been added.
	 *
	 * @since 2.9.0
	 *
	 * @param string $option Name of the added option.
	 * @param mixed  $value  Value of the option.
	 */
	do_action( 'added_option', $option, $value );
	return true;
}

笔记（Notes）