Don't overwrite data when I upload new using pandas dataframe and postgressql-CodePudding

I want to start uploading data to my PostgresSql table using pandas. I do the following,

import psycopg2
import pandas as pd
from sqlalchemy import create_engine

user = 'aaa'
passw= 'bbb'
host = 'ccc'
database = 'ddd'
conn_string = f'postgresql://{user}:{passw}@{host}/{database}'

df = pd.read_csv('20220817.csv')

db = create_engine(conn_string)
conn = db.connect()

table = 'tableTest'
df.to_sql(table, con=conn, if_exists='replace', index=False)

conn.close()

The problem is with this code I overwrite the previous data on my table. How can I upload new, without overwriting? I have if_exists=True but my new data is not the same because are time series and change the date and value.

Thank you!

CodePudding user response：

You can try by appending as follows:

df.to_sql(table, con=conn, if_exists='append', index=False)

Resource: https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.to_sql.html

CodePudding user response：

Replace the argument if_exists='replace' to if_exists='append'