SQL选择多个MAX和MIN - Python答案

【问题标题】：SQL selecting multiple MAX and MIN - PythonSQL选择多个MAX和MIN - Python
【发布时间】：2015-07-04 22:12:10
【问题描述】：

我有一个程序可以在数据库中存储学生的分数。我想为每个学生选择最高分。目前，只返回所有学生中得分最高的一名学生，而不是每个学生的最高分。谁能帮我解决这个问题？（仅供参考，有一个“分数”列，其中存储了分数列表）

def ClassSort():
myFile = sqlite3.connect("scores.db")
c = myFile.cursor()

clear()
classNo = input("Enter the class number you would like to sort... ")
clear()
type = input("How would you like to sort ? \n 1 - Highest score, with students in alphabetical order \n 2 - Highest score, highest to lowest \n 3 - Average score, highest to lowest \n... ")

if type == "1":
    c.execute('SELECT MIN(score), name FROM scores WHERE classNo = (?)', (classNo,))                
if type == "2":
    c.execute('SELECT MAX(score), name FROM scores WHERE classNo = (?)', (classNo,))
if type == "3":
    c.execute('SELECT AVG(score), name FROM scores WHERE classNo = (?)', (classNo,))        

row = c.fetchall()
row = ', '.join(map(str, row))
print(row)

myFile.commit()
myFile.close()

【问题讨论】：

标签： python sql database sqlite

【解决方案1】：

您需要添加GROUP BY 语句。 sql 中的聚合函数通常与GROUP BY 一起使用最有用。

SELECT MAX(score), name FROM scores WHERE classNo = (?) GROUP BY name

【讨论】：