order by a desc,b desc與order by a,b desc的區別

表爲： 通過下面sql看出 order by 默認是asc 。相當於select * from order_table order by id1 asc 通過下面兩個圖可知，  select * from order_table order by id1,id2 desc不等於 select * from order_table order by id1 desc,id2 desc. select

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