使用多个参数格式化字符串，以便 MySQL 可以处理它们答案

【问题标题】：Format string with multiple parameters so that MySQL can proces them使用多个参数格式化字符串，以便 MySQL 可以处理它们
【发布时间】：2020-04-30 11:52:06
【问题描述】：

我想知道如何格式化 API 返回的字符串，以便 Mysql 可以处理它。

这是我的 API 返回的字符串：bad_string = "History,Romance,Business & Money"

尝试 1：

cursor.execute("SELECT * FROM book WHERE scrape_category IN (%s) ORDER BY RAND() LIMIT 15", bad_string)

返回此消息：

Traceback (most recent call last):
  File "C:\PATH", line 23, in <module>
    cursor.execute("SELECT * FROM book WHERE scrape_category IN (%s) ORDER BY RAND() LIMIT 15", bad_string)
  File "C:\PATH\AppData\Roaming\Python\Python37\site-packages\mysql\connector\cursor_cext.py", line 259, in execute
    "Not all parameters were used in the SQL statement")
mysql.connector.errors.ProgrammingError: Not all parameters were used in the SQL statement

尝试 2：

bad_string_2 = "'Romance', 'History', 'Business & Money'"

cursor.execute("SELECT * FROM book WHERE scrape_category IN (%s) ORDER BY RAND() LIMIT 15", bad_string_2)

返回此消息：

Traceback (most recent call last):
  File "C:PATH", line 21, in <module>
    cursor.execute("SELECT * FROM book WHERE scrape_category IN (%s) ORDER BY RAND() LIMIT 15", bad_string_2)
  File "C:\PATH\AppData\Roaming\Python\Python37\site-packages\mysql\connector\cursor_cext.py", line 246, in execute
    prepared = self._cnx.prepare_for_mysql(params)
  File "C:\PATH\AppData\Roaming\Python\Python37\site-packages\mysql\connector\connection_cext.py", line 520, in prepare_for_mysql
    raise ValueError("Could not process parameters")
ValueError: Could not process parameters

这行得通：

cursor.execute("SELECT * FROM book WHERE scrape_category IN ('Romance', 'History', 'Business & Money') ORDER BY RAND() LIMIT 15")

当我这样做时查询有效：

cursor.execute("SELECT * FROM book WHERE scrape_category IN ('Romance', 'History', 'Business & Money') ORDER BY RAND() LIMIT 15")

如何格式化字符串并让 MySQL 返回结果？

【问题讨论】：

我应该更明确一点：您需要将bad_string 拆分为单独的值。最好在表单中执行此操作，然后将其发送到 Flask 视图。看看MultiDict.getlist() method，如果你多次使用同一个参数名，你可以得到一个列表，例如使用/preferred_categories?categories=Romance&categories=History&categories&Business%20%26%20Money 调用您的视图，然后使用categories = request.args.getlist('categories')。

标签： python mysql string where-in

【解决方案1】：

试试这样的：

filter ="History,Romance,Business & Money".split(',')
sqlcommand = "SELECT * FROM book WHERE scrape_category IN ({0})".format(
    ', '.join(['%s'] * len(filter)))
print(sqlcommand)
cursor.execute(sqlcommand, filter)

【讨论】：

这很好用！非常感谢！你成就了我的一天：D

【解决方案2】：

您的字符串值为： "History,Romance,Business & Money"

你需要这个：'Romance', 'History', 'Business & Money'

尝试类似bad_string = " 'Romance', 'History', 'Business & Money' "

希望对你有帮助...

【讨论】：