is_blog_installed()

确定是否已安装WordPress。
Determines whether WordPress is already installed.

目录锚点：#说明#返回#源码

说明（Description）

将首先检查缓存。如果您有一个缓存插件，它保存缓存值，那么这将工作。如果使用默认的WordPress缓存，而数据库消失，则可能会出现问题。

检查是否安装了WordPress的“siteurl”选项。

有关此主题函数和类似主题函数的更多信息，请参阅主题开发人员手册中的条件标记文章。

返回（Return）

（bool）站点是否已安装。

源码（Source）

/**
 * Test whether blog is already installed.
 *
 * The cache will be checked first. If you have a cache plugin, which saves
 * the cache values, then this will work. If you use the default WordPress
 * cache, and the database goes away, then you might have problems.
 *
 * Checks for the 'siteurl' option for whether WordPress is installed.
 *
 * @since 2.1.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @return bool Whether the blog is already installed.
 */
function is_blog_installed() {
	global $wpdb;

	/*
	 * Check cache first. If options table goes away and we have true
	 * cached, oh well.
	 */
	if ( wp_cache_get( 'is_blog_installed' ) )
		return true;

	$suppress = $wpdb->suppress_errors();
	if ( ! defined( 'WP_INSTALLING' ) ) {
		$alloptions = wp_load_alloptions();
	}
	// If siteurl is not set to autoload, check it specifically
	if ( !isset( $alloptions['siteurl'] ) )
		$installed = $wpdb->get_var( "SELECT option_value FROM $wpdb->options WHERE option_name = 'siteurl'" );
	else
		$installed = $alloptions['siteurl'];
	$wpdb->suppress_errors( $suppress );

	$installed = !empty( $installed );
	wp_cache_set( 'is_blog_installed', $installed );

	if ( $installed )
		return true;

	// If visiting repair.php, return true and let it take over.
	if ( defined( 'WP_REPAIRING' ) )
		return true;

	$suppress = $wpdb->suppress_errors();

	/*
	 * Loop over the WP tables. If none exist, then scratch install is allowed.
	 * If one or more exist, suggest table repair since we got here because the
	 * options table could not be accessed.
	 */
	$wp_tables = $wpdb->tables();
	foreach ( $wp_tables as $table ) {
		// The existence of custom user tables shouldn't suggest an insane state or prevent a clean install.
		if ( defined( 'CUSTOM_USER_TABLE' ) && CUSTOM_USER_TABLE == $table )
			continue;
		if ( defined( 'CUSTOM_USER_META_TABLE' ) && CUSTOM_USER_META_TABLE == $table )
			continue;

		if ( ! $wpdb->get_results( "DESCRIBE $table;" ) )
			continue;

		// One or more tables exist. We are insane.

		wp_load_translations_early();

		// Die with a DB error.
		$wpdb->error = sprintf( __( 'One or more database tables are unavailable. The database may need to be repaired.' ), 'maint/repair.php?referrer=is_blog_installed' );
		dead_db();
	}

	$wpdb->suppress_errors( $suppress );

	wp_cache_set( 'is_blog_installed', false );

	return false;
}