wpdb::has_cap() │ public │ WP 2.7.0

Determines whether the database or WPDB supports a particular feature.

Capability sniffs for the database server and current version of WPDB.

Database sniffs are based on the version of MySQL the site is using.

WPDB sniffs are added as new features are introduced to allow theme and plugin developers to determine feature support. This is to account for drop-ins which may introduce feature support at a different time to WordPress.

Method of the class: wpdb{}

No Hooks.

Return

true|false. True when the database feature is supported, false otherwise.

Usage

global $wpdb;
$wpdb->has_cap( $db_cap );

$db_cap(string) (required)

The feature to check for. Accepts 'collation', 'group_concat', 'subqueries', 'set_charset', 'utf8mb4', 'utf8mb4_520', or 'identifier_placeholders'.

Notes

• See: wpdb::db_version()

Changelog

wpdb::has_cap() wpdb::has cap code ^{WP 6.5.2}

public function has_cap( $db_cap ) {
	$db_version     = $this->db_version();
	$db_server_info = $this->db_server_info();

	/*
	 * Account for MariaDB version being prefixed with '5.5.5-' on older PHP versions.
	 *
	 * Note: str_contains() is not used here, as this file can be included
	 * directly outside of WordPress core, e.g. by HyperDB, in which case
	 * the polyfills from wp-includes/compat.php are not loaded.
	 */
	if ( '5.5.5' === $db_version && false !== strpos( $db_server_info, 'MariaDB' )
		&& PHP_VERSION_ID < 80016 // PHP 8.0.15 or older.
	) {
		// Strip the '5.5.5-' prefix and set the version to the correct value.
		$db_server_info = preg_replace( '/^5\.5\.5-(.*)/', '$1', $db_server_info );
		$db_version     = preg_replace( '/[^0-9.].*/', '', $db_server_info );
	}

	switch ( strtolower( $db_cap ) ) {
		case 'collation':    // @since 2.5.0
		case 'group_concat': // @since 2.7.0
		case 'subqueries':   // @since 2.7.0
			return version_compare( $db_version, '4.1', '>=' );
		case 'set_charset':
			return version_compare( $db_version, '5.0.7', '>=' );
		case 'utf8mb4':      // @since 4.1.0
			if ( version_compare( $db_version, '5.5.3', '<' ) ) {
				return false;
			}

			$client_version = mysqli_get_client_info();

			/*
			 * libmysql has supported utf8mb4 since 5.5.3, same as the MySQL server.
			 * mysqlnd has supported utf8mb4 since 5.0.9.
			 *
			 * Note: str_contains() is not used here, as this file can be included
			 * directly outside of WordPress core, e.g. by HyperDB, in which case
			 * the polyfills from wp-includes/compat.php are not loaded.
			 */
			if ( false !== strpos( $client_version, 'mysqlnd' ) ) {
				$client_version = preg_replace( '/^\D+([\d.]+).*/', '$1', $client_version );
				return version_compare( $client_version, '5.0.9', '>=' );
			} else {
				return version_compare( $client_version, '5.5.3', '>=' );
			}
		case 'utf8mb4_520': // @since 4.6.0
			return version_compare( $db_version, '5.6', '>=' );
		case 'identifier_placeholders': // @since 6.2.0
			/*
			 * As of WordPress 6.2, wpdb::prepare() supports identifiers via '%i',
			 * e.g. table/field names.
			 */
			return true;
	}

	return false;
}