我正尝试将'financies'数据库的'register'表中的'date'变量转换为日期格式。
我有下面的Python代码，它可以运行并且不会抛出任何错误。除了“update register”语句外，其他都正常工作。

import sqlite3
import pandas as pd

conn = sqlite3.connect('C:\\SQLite\\finances.db')
cursor = conn.cursor()
cursor_obj = conn.cursor()

# read the csv file
df = pd.read_csv('C:\\SQLite\\finance_register.csv')

# write to SQLite
df.to_sql("register", conn, if_exists="replace", index=False)

# change column names
cursor.execute('''alter table register rename 'Category Group' to category_group''')
cursor.execute('''alter table register rename 'Account' to account''')
cursor.execute('''alter table register rename 'Flag' to flag''')
cursor.execute('''alter table register rename 'Date' to date''')
cursor.execute('''alter table register rename 'Payee' to payee''')
cursor.execute('''alter table register rename 'Category Group/Category' to category_group_category''')
cursor.execute('''alter table register rename 'Category' to category''')
cursor.execute('''alter table register rename 'Memo' to memo''')
cursor.execute('''alter table register rename 'Outflow' to outflow''')
cursor.execute('''alter table register rename 'Inflow' to inflow''')
cursor.execute('''alter table register rename 'Cleared' to cleared''')

cursor.execute('''update register set date = substr(date, 7, 4) || '-' || substr(date, 1, 2) || '-' || substr(date, 4, 2)''')
    
conn.close()

字符串
当我在SQLite Studio中执行以下代码时，更改生效：

update register set date=substr(date, 7, 4) || '-' || substr(date, 1, 2) || '-' || substr(date, 4, 2);

型
我不知道为什么Python脚本不工作。有什么想法吗