SQL查询排序问题

[zhuhao]

SELECT * , group_concat( ' ' , concat_ws( ' X ', `sku` , `quantity-purchased` ) , ' ' ),group_concat(' ' , `order_id` , ' ') FROM ( select * from `sale_orders` order by `sku`) T WHERE `shipments` =0 AND `number` =$id GROUP BY `recipient-name` , `ship-address-1` ORDER BY `sku`

以下为查询的结果：

ship name group_concat( ' ' , concat_ws( ' X ', `sku` , `quantity-purchased` ) , ' ' )
001-01 wang A0015-00-04-23 X 1
002-02 liu A0041-00-WW-25 X 1 , A0042-00-AC-25 X 1
003-03 li A0041-00-WW-25 X 1 , A0042-00-AC-25 X 1 , A0256-00-O6-34 X 1
004-04 fang A0041-00-WW-25 X 1 ,A0042-00-AC-25 X 1 , A0217-00-SI-33 X 1

请问怎么在此基础上再按group_concat( ' ' , concat_ws( ' X ', `sku` , `quantity-purchased` ) , ' ' )字段的SKU个数来排序（就是字符串长度）

[ACMAIN_CHM]

SELECT * , group_concat( ' ' , concat_ws( ' X ', `sku` , `quantity-purchased` ) , ' ' ),group_concat(' ' , `order_id` , ' ') FROM ( select * from `sale_orders` order by `sku`) T WHERE `shipments` =0 AND `number` =$id GROUP BY `recipient-name` , `ship-address-1` ORDER BY `sku`, length(group_concat( ' ' , concat_ws( ' X ', `sku` , `quantity-purchased` ) , ' ' ))

[rucypli]

order by length(group_concat( ' ' , concat_ws( ' X ', `sku` , `quantity-purchased` ) , ' ' ))