带有 SQLAlchemy 的 Pandas to_sql 不能用于 mysql

Question

我在当前版本中遇到 pandas to_sql 问题。 我已经像这样使用 SQLAchemy 设置了创建引擎

db_url = "mysql+mysqlconnector://{USER}:{PWD}@{HOST}/{DBNAME}"

db_url = db_url.format(
    USER = "root",
    PWD = "root",
    HOST = "127.0.0.1:3306",
    DBNAME = "report"
)
engine = create_engine(db_url, echo=False)

当使用 pandas to_sql 时，

with engine.begin() as connection:
    df.to_sql('dim_date', con=connection, index=False, if_exists='replace')

我遇到这样的错误

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Cell In[10], line 2
      1 with engine.begin() as connection:
----> 2     df.to_sql('dim_date', con=connection, index=False, if_exists='replace')

File /usr/local/lib/python3.11/site-packages/pandas/util/_decorators.py:333, in deprecate_nonkeyword_arguments.<locals>.decorate.<locals>.wrapper(*args, **kwargs)
    327 if len(args) > num_allow_args:
    328     warnings.warn(
    329         msg.format(arguments=_format_argument_list(allow_args)),
    330         FutureWarning,
    331         stacklevel=find_stack_level(),
    332     )
--> 333 return func(*args, **kwargs)

File /usr/local/lib/python3.11/site-packages/pandas/core/generic.py:3081, in NDFrame.to_sql(self, name, con, schema, if_exists, index, index_label, chunksize, dtype, method)
   2886 """
   2887 Write records stored in a DataFrame to a SQL database.
   2888 
   (...)
   3077 [(1,), (None,), (2,)]
   3078 """  # noqa: E501
   3079 from pandas.io import sql
-> 3081 return sql.to_sql(
   3082     self,
   3083     name,
   3084     con,
   3085     schema=schema,
   3086     if_exists=if_exists,
   3087     index=index,
   3088     index_label=index_label,
   3089     chunksize=chunksize,
   3090     dtype=dtype,
   3091     method=method,
   3092 )

File /usr/local/lib/python3.11/site-packages/pandas/io/sql.py:842, in to_sql(frame, name, con, schema, if_exists, index, index_label, chunksize, dtype, method, engine, **engine_kwargs)
    837     raise NotImplementedError(
    838         "'frame' argument should be either a Series or a DataFrame"
    839     )
    841 with pandasSQL_builder(con, schema=schema, need_transaction=True) as pandas_sql:
--> 842     return pandas_sql.to_sql(
    843         frame,
    844         name,
    845         if_exists=if_exists,
    846         index=index,
    847         index_label=index_label,
    848         schema=schema,
    849         chunksize=chunksize,
    850         dtype=dtype,
    851         method=method,
    852         engine=engine,
    853         **engine_kwargs,
    854     )

File /usr/local/lib/python3.11/site-packages/pandas/io/sql.py:2851, in SQLiteDatabase.to_sql(self, frame, name, if_exists, index, index_label, schema, chunksize, dtype, method, engine, **engine_kwargs)
   2840             raise ValueError(f"{col} ({my_type}) not a string")
   2842 table = SQLiteTable(
   2843     name,
   2844     self,
   (...)
   2849     dtype=dtype,
   2850 )
-> 2851 table.create()
   2852 return table.insert(chunksize, method)

File /usr/local/lib/python3.11/site-packages/pandas/io/sql.py:984, in SQLTable.create(self)
    983 def create(self) -> None:
--> 984     if self.exists():
    985         if self.if_exists == "fail":
    986             raise ValueError(f"Table '{self.name}' already exists.")

File /usr/local/lib/python3.11/site-packages/pandas/io/sql.py:970, in SQLTable.exists(self)
    969 def exists(self):
--> 970     return self.pd_sql.has_table(self.name, self.schema)

File /usr/local/lib/python3.11/site-packages/pandas/io/sql.py:2866, in SQLiteDatabase.has_table(self, name, schema)
   2855 wld = "?"
   2856 query = f"""
   2857 SELECT
   2858     name
   (...)
   2863     AND name={wld};
   2864 """
-> 2866 return len(self.execute(query, [name]).fetchall()) > 0

File /usr/local/lib/python3.11/site-packages/pandas/io/sql.py:2673, in SQLiteDatabase.execute(self, sql, params)
   2671     raise TypeError("Query must be a string unless using sqlalchemy.")
   2672 args = [] if params is None else [params]
-> 2673 cur = self.con.cursor()
   2674 try:
   2675     cur.execute(sql, *args)

AttributeError: 'Connection' object has no attribute 'cursor'

就像 pandas 库使用默认的 SQLiteDatabase 执行器一样。 有哪位朋友能解决我的问题吗？

我的代码能够使用 pandas to_sql 插入 MySQL 数据库有什么问题？

Answer 1

我认为您使用的是旧版本的

SQLAlchemy

（1.x？），因此它无法与最新版本的

Pandas

一起使用。您必须升级您的

SQLAlchemy

版本:

[...]$ pip install -U sqlalchemy

注意：我尝试了你的代码，它与

Pandas==2.2.0

和

sqlalchemy==2.0.25

配合得很好。

更多信息：

• Pandas to_sql 到 sqlite 返回“Engine”对象没有属性“cursor”
  该解决方案无法与您实际版本的 Pandas 一起使用（所以它不是骗局）