wpdb::has_cap( string $db_cap ): bool

Determines whether the database or WPDB supports a particular feature.


Description

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.

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See also


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Parameters

$db_cap string Required
The feature to check for. Accepts 'collation', 'group_concat', 'subqueries', 'set_charset', 'utf8mb4', or 'utf8mb4_520'.

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Return

bool True when the database feature is supported, false otherwise.


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Source

File: wp-includes/class-wpdb.php. View all references

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.
	if ( '5.5.5' === $db_version && str_contains( $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;
			}
			if ( $this->use_mysqli ) {
				$client_version = mysqli_get_client_info();
			} else {
				$client_version = mysql_get_client_info();
			}

			/*
			 * libmysql has supported utf8mb4 since 5.5.3, same as the MySQL server.
			 * mysqlnd has supported utf8mb4 since 5.0.9.
			 */
			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', '>=' );
	}

	return false;
}


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Changelog

Changelog
Version Description
4.6.0 Added support for the 'utf8mb4_520' feature.
4.1.0 Added support for the 'utf8mb4' feature.
2.7.0 Introduced.

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