如何在sqlite數據庫中檢查用戶名？ Python

Question

我正在嘗試檢查數據庫中的用戶名，當我這樣做時，它適用於第一個用戶名，但在它不起作用之后，我想我明白為什么，但我無法找到替代方案。 這是我的代碼：

import sqlite3
conn = sqlite3.connect('tutorial.db')
c = conn.cursor()
def username():
    global limit
    global usernameinput
    usernameinput = input("What would you like your username to be?")
    limit = 0
    select_all_tasks(conn)
def create_table():
    c.execute('CREATE TABLE IF NOT EXISTS stuffToPlot(username TEXT, 
    password TEXT)')
    conn.close
def select_all_tasks(conn):
    global limit
    global passwordinput
    global rows
    c.execute("SELECT * FROM stuffToPlot")
    rows = c.fetchall()
    for row in rows:
        print(row)
    if usernameinput in row:
        print("Username Taken")
        username()
    else:
        if limit < 1:
            passwordinput = input("What would you like your password to 
            be?")
            limit = limit + 1
def data_entry():
    global passwordinput
    global row
    c.execute("INSERT INTO stuffToPlot VALUES(?, ?);",(usernameinput, 
    passwordinput))
    conn.commit()
    c.close()
    conn.close()


create_table()
username()
select_all_tasks(conn)
data_entry()

沒有錯誤，只是沒有注冊用戶名已經在數據庫中。

Answer 1

您需要縮進 if 語句和以下所有行以使其工作，否則只測試最后一行。

for row in rows:
    print(row)
    if usernameinput in row:
        print("Username Taken")

---

你也可以讓它更簡單：

# select only the field "username" from the table
c.execute("SELECT username FROM stuffToPlot") 
# build a set with all names, from the results given as [('name1',), ('name2',), ('name3',)]
names = {name[0] for name in c.fetchall()} 
if usernameinput in names:  
    print("Username Taken")
    username()
else:
    if limit < 1: