MySQL Query get ranking method (absolutely valid)

http://blog.csdn.net/k8080880/article/details/11253305

Select

Case if Pid=0 Then
When the case is @prevType =quetype_id then @rank: [Email protected]+1
When @prevType: =quetype_id then @rank: =1 End
else Que_sort end as Que_sort2,

A.*

From
SELECT
0 exam_id,
Q.pid,

Q.que_sort,

@prevType: =q.quetype_id

From
T_home_question rel LEFT Join
T_question Q on (rel.question_id=q.question_id or Rel.question_id=q.pid)
WHERE rel.home_id=320 ORDER BY Quetype_id,pid
) A, (SELECT @rank: =0, @prevType: =null) B

MySQL Query get ranking method (absolutely valid)