Pl/SQL 在没有排名函数的情况下将最高 GPA 排名到最低的程序

Question

Pl/SQL procedure to rank highest GPA to lowest

我指的是上面的问题。是否可以在没有排名功能的情况下对学生及其 GPA 进行排名？

FETCH c1 INTO queryResult; 
 INSERT INTO GPA VALUES (queryResult.snum, queryResult.sname, rank,queryResult.OrderFrequency);
 rank := rank + 1;
 EXIT WHEN k = rank;
 END LOOP;
 CLOSE c1;
 COMMIT;
END;

Answer 1

Is it possible to rank a student and their GPA without the rank function?

是的，使用带左自连接、分组依据和计数的普通 SQL。
但预计会比使用 RANK 函数

的版本慢

现场演示：http://sqlfiddle.com/#!4/bde51/7

SELECT s1. snum,
       s1.sname,
       s1.gpa,
       count( s2.gpa ) + 1 as rank
FROM students s1
LEFT JOIN students s2
ON s1.GPA < s2.GPA
GROUP BY s1. snum,
         s1.sname,
         s1.gpa
ORDER BY 4;

| SNUM |     SNAME | GPA | RANK |
|------|-----------|-----|------|
|    6 | Student 6 |   4 |    1 |
|    4 | Student 4 |   3 |    2 |
|    3 | Student 3 |   2 |    3 |
|    1 | Student 1 |   2 |    3 |
|    2 | Student 2 |   1 |    5 |
|    5 | Student 5 |   1 |    5 |

select snum,
       sname, 
       GPA, 
       RANK() OVER (ORDER BY GPA desc) as srank
from students
ORDER BY 4

| SNUM |     SNAME | GPA | SRANK |
|------|-----------|-----|-------|
|    6 | Student 6 |   4 |     1 |
|    4 | Student 4 |   3 |     2 |
|    1 | Student 1 |   2 |     3 |
|    3 | Student 3 |   2 |     3 |
|    5 | Student 5 |   1 |     5 |
|    2 | Student 2 |   1 |     5 |

Pl/SQL 在没有排名函数的情况下将最高 GPA 排名到最低的程序

Pl/SQL procedure to rank highest GPA to lowest without Rank Function

sql

plsql

cursor

oracle10g