在一条语句中组合两个sql查询

Question

l have a list of students score, i want to find the rank for each student according to his average

here is the table

steps to find the student rank.

1. create the view of average score for each student

     CREATE VIEW mid_view as SELECT *,AVG(score) as score from midterm_result group by student_id 

2.. find the rank

     SELECT * , @rank := if( @last = average, @rank , @seq ) AS rank, @seq := @seq +1,   
     @last := average
    FROM mid_view
    ORDER BY average DESC

result is

my target is to reduce the steps, i want to reach at final result without creating the mid_view

How can i combine these to queries in single statement?

Answer 1

You could just include the first query as a sub query of the second one:

SELECT m.*, @rank := if(@last = average, @rank, @seq) AS rank, 
       @seq := @seq +1, @last := average
FROM 
(
  SELECT *, AVG(score) as score 
  from midterm_result 
  group by student_id
) m
ORDER BY average DESC