查询一个sqlite3数据库

Question

我正在尝试编写一个程序来查询数据库。 该数据库是golfDB，它由一个称为玩家的表组成，具有5个字段：名称（玩家的名字），totalGross（每个回合的总得分之和），totalRounds（打入的回合数），标准杆（标准杆总数） ，以及小鸟（小鸟总数）。我的程序需要输出标准杆最多的球员，输入球员的平均得分（totalGross / totalRounds），并按总得分从高到低的顺序列出球员现在，我还没有真正使用最多的pars函数或排序分数的函数来工作。我的平均分数函数有问题。我遇到了这个错误，而且我不确定如何修理它：

Traceback (most recent call last):
  File "/Users/tinydancer9454/Documents/python/golfDBuserInterface.py", line 46, in <module>
    main()
  File "/Users/tinydancer9454/Documents/python/golfDBuserInterface.py", line 40, in main
    queryDBavgScore(cursor)
  File "/Users/tinydancer9454/Documents/python/golfDBuserInterface.py", line 29, in queryDBavgScore
    answer = totalGrossScore/ totalRoundsScore
TypeError: unsupported operand type(s) for /: 'tuple' and 'tuple'

到目前为止，这是我的代码：

import sqlite3

def getDBCursor(DB):
    """obtain and return a cursor for the database DB"""
    conn= sqlite3.connect('/Users/tinydancer9454/Documents/python/golfDB')
    cursor= conn.cursor()
    return cursor

def queryDBpars(cursor):
    """find out which player had the most pars"""
    cursor.execute('select name from players where pars >= 0')


def queryDBavgScore(cursor):
    """find the average score of inputed player"""
    player= input("Please enter the player's name: ")
    cursor.execute('select totalGross from players where name = ?', (player,))
    totalGrossScore = cursor.fetchone()
    cursor.execute('select totalRounds from players where name = ?', (player,))
    totalRoundsScore = cursor.fetchone()
    answer = totalGrossScore/ totalRoundsScore
    print('The average score for', player, 'is', answer)

def queryDBplayers(cursor):
    """lists the players in order of their total gross score"""


def main():
    """obtain cursor and query the database: golfDB"""
    cursor= getDBCursor('golfDB')
    queryDBpars(cursor)
    queryDBavgScore(cursor)
    queryDBplayers(cursor)
    cursor.close()

Answer 1

SQLite3的fetchone返回一个元组，因此在尝试潜水之前，您需要获取第一项，否则本质上您将划分两个元组。

totalGrossScore = cursor.fetchone()[0]
totalRoundsScore = cursor.fetchone()[0]

在这种情况下，您的查询仅从一个字段获取数据，但请记住，查询可能返回的不止一个字段，这就是fetchone返回元组的原因。