1.使用“用户”凭据时出现权限错误：错误消息表明指定的用户帐户没有在“test”数据库中创建新表所需的权限。若要解决此问题，应授予“user”帐户将数据插入现有表所需的权限。可以使用SQL Server Management Studio或通过执行适当的SQL命令将目标表的INSERT权限授予“user”帐户来执行此操作。
1.使用“admin”凭据时替换现有表：默认情况下，如果指定的表不存在，Pandas中的to_sql方法会创建一个新表。如果要将数据追加到现有表中，则应将to_sql函数调用中的if_exists参数修改为'append'。此外，可以使用dtype参数指定目标表中的列数据类型，以确保它们与原始表结构匹配。

from sqlalchemy import create_engine

def write_to_database(self, s_table, df):
    s_host = 'localhost'
    s_driver = 'SQL Server'
    port = 1433
    s_database = 'test'
    d_users = {
        'admin': ('censored', 'censored'),
        'user': ('censored', 'censored'),
    }
    s_username, s_pw = d_users.get('user', ('empty', 'empty'))
    mysql_engine = create_engine(
        f"mssql+pyodbc://{s_username}:{s_pw}@{s_host}:{port}/{s_database}?driver={s_driver}",
        pool_reset_on_return=None,  # disable default reset-on-return scheme
        use_setinputsizes=False
    )
    
    with mysql_engine.connect() as con:
        # Get the column data types from the existing table
        table_info = con.execute(f"SELECT TOP 1 * FROM {s_table}")
        column_types = {column[0]: column[1] for column in table_info.cursor_description}
        
        # Append data to the existing table
        df.to_sql(name=s_table, con=con, if_exists='append', index=False, dtype=column_types)

确保将s_table替换为目标表的实际名称。代码从现有表中检索列数据类型，并在编写DataFrame时使用它们以确保兼容性。

from sqlalchemy import create_engine, inspect

def write_to_database(self, s_table, df):
    s_host = 'localhost'
    s_driver = 'SQL Server'
    port = 1433
    s_database = 'test'
    d_users = {
        'admin': ('censored', 'censored'),
        'user': ('censored', 'censored'),
    }
    s_username, s_pw = d_users.get('user', ('empty', 'empty'))
    mysql_engine = create_engine(
        f"mssql+pyodbc://{s_username}:{s_pw}@{s_host}:{port}/{s_database}?driver={s_driver}",
        pool_reset_on_return=None,  # disable default reset-on-return scheme
        use_setinputsizes=False
    )
    
    with mysql_engine.connect() as con:
        inspector = inspect(con)
        
        if s_table not in inspector.get_table_names():
            raise ValueError(f"The table '{s_table}' does not exist in the database.")
        
        # Get the column information from the existing table
        columns = inspector.get_columns(s_table)
        column_names = [column['name'] for column in columns]
        
        # Filter DataFrame columns to match the existing table structure
        df = df[column_names]
        
        # Generate the INSERT INTO statement and append the data to the existing table
        insert_statement = f"INSERT INTO {s_table} ({', '.join(column_names)}) VALUES (?, ?, ?)"
        data = [tuple(row) for row in df.values.tolist()]
        con.execute(insert_statement, data)