Question

我现在正在使用realypython Book2学习Python（Flask）。

我遇到了一个阻止我使用db_migrate.py运行数据库迁移的错误。它说没有表格＆＃34;任务＆＃34;。

我添加了＃34; connection.commit（）＆＃34;进入代码，然后它运行正常。为什么我需要使用＆＃34; commit（）＆＃34;？

强制更改表

感谢。

https://github.com/realpython/book2-exercises/edit/master/flasktaskr-02/project

# project/db_migrate.py


from views import db
from _config import DATABASE_PATH

import sqlite3
from datetime import datetime

with sqlite3.connect(DATABASE_PATH) as connection:

    # get a cursor object used to execute SQL commands
    c = connection.cursor()

    # temporarily change the name of tasks table
    c.execute("""ALTER TABLE tasks RENAME TO old_tasks""")
    connection.commit()
    # recreate a new tasks table with updated schema
    db.create_all()

    # retrieve data from old_tasks table
    c.execute("""SELECT name, due_date, priority,
                status FROM old_tasks ORDER BY task_id ASC""")

    # save all rows as a list of tuples; set posted_date to now and user_id to 1
    data = [(row[0], row[1], row[2], row[3],
            datetime.now(), 1) for row in c.fetchall()]

    # insert data to tasks table
    c.executemany("""INSERT INTO tasks (name, due_date, priority, status,
                    posted_date, user_id) VALUES (?, ?, ?, ?, ?, ?)""", data)

    # delete old_tasks table
    c.execute("DROP TABLE old_tasks")

python sqlite alter table失败而没有提交

0 个答案: