[Solved] how to select from this table and add average value and then sort [duplicate]

by 


select * from <your query> order by PERC

wich :

select * from (

select no, STUD_ID,CLASS,LESSON, AVG(PERC) as PERC,SUM(CNT) as CNT from t_lesson where LESSON='CHEM' group by CLASS
union all
select no,STUD_ID,CLASS,'AVERAGE' as LESSON, AVG(PERC) as PERC, SUM(CNT) as CNT from t_lesson where LESSON='CHEM' group by LESSON

) as sub order by PERC DESC

solved how to select from this table and add average value and then sort [duplicate]