wpdb::set_charset( mysqli $dbh, string $charset = null, string $collate = null )

917	public function set_charset( $dbh, $charset = null, $collate = null ) {918		if ( ! isset( $charset ) ) {919			$charset = $this->charset;920		}921		if ( ! isset( $collate ) ) {922			$collate = $this->collate;923		}924		if ( $this->has_cap( 'collation' ) && ! empty( $charset ) ) {925			$set_charset_succeeded = true;926 927			if ( function_exists( 'mysqli_set_charset' ) && $this->has_cap( 'set_charset' ) ) {928				$set_charset_succeeded = mysqli_set_charset( $dbh, $charset );929			}930 931			if ( $set_charset_succeeded ) {932				$query = $this->prepare( 'SET NAMES %s', $charset );933				if ( ! empty( $collate ) ) {934					$query .= $this->prepare( ' COLLATE %s', $collate );935				}936				mysqli_query( $dbh, $query );937			}938		}939	}