4 _# m' k$ r' |" X5 ]' E3 m! E4 ^1 }2 fselect distinct classname from practice where coursename='网络营销' order by code---------------- ' N5 s, r, I+ L4 v, I* |“如果指定了 SELECT DISTINCT,那么 ORDER BY 子句中的项就必须出现在选择列表中。”& F( `( H. j+ R
, _% S8 ^0 L6 u8 p% q改成这种 . @+ P9 z/ A; G4 g& G5 Q, m9 d+ X" gselect classname from(select max(code)as code ,classname from practice where coursename='网络营销' group by classname)a order by code