无法使用pandas读取数据到csv文件

Question

我有一个下面的数据表需要读取表中的整个数据到pandas执行累计求和和平均后需要生成CSV文件[逗号分隔的文件，文件头]

NAME,AGE,MARKS
A1,12,40
B1,13,54
C1,15,67
D1,11,41
E1,16,59
F1,10,60

我试着写卡住了

import cx_Oracle
import pandas as pd
try : 
sq='select * from emp'
conn=cx_Oracle.cpnnect(myconnection)
fd=pd.read_sql(sql,con=conn)
fd['CUM_SUM'] = fd['MARKS'].cumsum()
fd['AVG'] = fd['MARKS'].expanding().mean()
fd.to_csv('file.csv', index=False)
except Exception as er:
print(er)

期望输出的csv文件头

NAME,AGE,MARKS,CUM_SUM,AVG
A1,12,40,40,40
B1,13,54,94,47
C1,15,67,161,53.66
D1,11,41,202,50.5
E1,16,59,261,43.5
F1,10,60,321,45.85

当我执行print(fd)时，它给出如下输出

NAME ..CUM,AVG
A1,..,40,40
B1,..,94,47
C1,..,161,53.66
D1,..,202,50.5
E1,..,261,43.5
F1,..,321,45.85

Answer 1

import sqlalchemy
import psycopg2
conn = 'postgresql+psycopg2://DB_USER:DB_PASS@DB_HOST:5432/DB_NAME'     # 5432 = DB_PORT
# Connect to DB
engine = sqlalchemy.create_engine(conn)
connect = engine.connect()
inspector = sqlalchemy.inspect(engine)
# inspector.get_table_names()
# Read data from table_name and add to data-frame
df = pd.read_sql("select * from table_name", connect)
# df.head(10)
# calculation
# Write to csv with headers and comma delimiter
df.to_csv('filename.csv', sep=',', header=True)

.to_csv文件:https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.to_csv.html