使用Python在SQLite中插入行后如何检索插入的ID? [英] How to retrieve inserted id after inserting row in SQLite using Python?

问题描述

如何在使用 Python 在 SQLite 中插入行后检索插入的 id?我有这样的桌子:

How to retrieve inserted id after inserting row in SQLite using Python? I have table like this:

id INT AUTOINCREMENT PRIMARY KEY,
username VARCHAR(50),
password VARCHAR(50)

我插入一个包含示例数据 username="test" 和 password="test" 的新行.如何以交易安全的方式检索生成的 id?这是针对网站解决方案，其中两个人可能同时插入数据.我知道我可以获得最后读取的行，但我认为这不是事务安全的.有人可以给我一些建议吗?

I insert a new row with example data username="test" and password="test". How do I retrieve the generated id in a transaction safe way? This is for a website solution, where two people may be inserting data at the same time. I know I can get the last read row, but I don't think that is transaction safe. Can somebody give me some advice?

推荐答案

您可以使用 cursor.lastrowid(请参阅可选数据库 API扩展名"):

You could use cursor.lastrowid (see "Optional DB API Extensions"):

connection=sqlite3.connect(':memory:')
cursor=connection.cursor()
cursor.execute('''CREATE TABLE foo (id integer primary key autoincrement ,
                                    username varchar(50),
                                    password varchar(50))''')
cursor.execute('INSERT INTO foo (username,password) VALUES (?,?)',
               ('test','test'))
print(cursor.lastrowid)
# 1

如果两个人同时插入，只要他们使用不同的cursor，cursor.lastrowid 将返回id 对于 cursor 插入的最后一行:

If two people are inserting at the same time, as long as they are using different cursors, cursor.lastrowid will return the id for the last row that cursor inserted:

cursor.execute('INSERT INTO foo (username,password) VALUES (?,?)',
               ('blah','blah'))

cursor2=connection.cursor()
cursor2.execute('INSERT INTO foo (username,password) VALUES (?,?)',
               ('blah','blah'))

print(cursor2.lastrowid)        
# 3
print(cursor.lastrowid)
# 2

cursor.execute('INSERT INTO foo (id,username,password) VALUES (?,?,?)',
               (100,'blah','blah'))
print(cursor.lastrowid)
# 100

请注意，当您使用 executemany 一次插入多于一行时，lastrowid 返回 None:

Note that lastrowid returns None when you insert more than one row at a time with executemany:

cursor.executemany('INSERT INTO foo (username,password) VALUES (?,?)',
               (('baz','bar'),('bing','bop')))
print(cursor.lastrowid)
# None

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