元组问题的python mysql更新功能，我再次需要您的帮助 [英] python mysql update function from tuple issue, I need your help again

问题描述

我想更新数据库中十分之几的条目. 我的想法如下，很遗憾，出现以下错误.

I would like to update several 10th of entries in my database. My idea is as follows, unfortunately, I get the following error.

我试图将其转换为字符串，但是它不起作用.

I tried to convert to a string, but it does not work.

有什么主意吗?

TypeError:必须是字符串或只读缓冲区，而不是元组

TypeError: must be string or read-only buffer, not tuple

lookup={
'Gigi':'Gigi Hofleitner',
'Horst':'Horst Sergio'
}

for i in lookup:
    sql="UPDATE namen SET Name = '%s' WHERE `Name` = '%s'",((lookup[i]),i)
    cursor.execute(sql)
    connection.commit()

推荐答案

cursor.execute()期望一个sql语句(作为字符串)和一个可选的值序列，因此应该是:

cursor.execute()expects a sql statement (as string) and an optional sequence of values, so it should have been either:

# this build a (statement, (values,....)) tuple
args = "UPDATE namen SET Name = '%s' WHERE `Name` = '%s'",(lookup[i],i)

# so you need positional arguments unpacking:
cursor.execute(*args) 

或

sql = "UPDATE namen SET Name = '%s' WHERE `Name` = '%s'"
cursor.execute(sql, (lookup[i],i))

对于经过清理和可读性更高的版本:

For a sanitized and more readable version:

lookup={
    'Gigi':'Gigi Hofleitner',
    'Horst':'Horst Sergio'
}

# no need to create the same invariant string again and agin
sql="UPDATE namen SET Name=%s WHERE Name=%s"

for oldname, newname in lookup.items():
    cursor.execute(sql, (newname, oldname))

# better to commit only once    
connection.commit()

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