Question

我有这张桌子

[1|Sub1|Mark1|Sub2|Mark2|Subj3|Mark3|...]
[2|JSP |85   |ASP |70   |PHP  |95   |...]

我需要两个最高学科的平均成绩吗？

例如

avg（Mark1，Mark3）;

Answer 1

你可能会问这个吗？

SELECT ID,
  (SELECT AVG(v) 
   FROM (VALUES (Mark1), (Mark2), (Mark3), (Mark4), (Mark5)) AS value(v)) as [AverageMarks]
FROM Table1

如果您仅在3个主题中寻找2个最高主题的平均值，则尝试此操作。

SELECT ID,
  (SELECT (SUM(v)-MIN(V))/2
   FROM (VALUES (Mark1), (Mark2), (Mark3)) AS value(v)) as [AverageMarks]
FROM Table1

FIDDLE DEMO

Answer 2

请考虑以下内容：

DROP TABLE IF EXIST my_table;

CREATE TABLE my_table
(subject CHAR(3) PRIMARY KEY
,mark INT NOT NULL
);

INSERT INTO my_table VALUES
('JSP',85),
('ASP',70),
('PHP',95);   

SELECT AVG(a.mark)
  FROM 
     ( SELECT mark FROM my_table ORDER BY mark DESC LIMIT 2 ) a;

+-------------+
| AVG(a.mark) |
+-------------+
|     90.0000 |
+-------------+

计算多列中最大值的平均值

avg（Mark1，Mark3）;

2 个答案: